View source for Sexual orientation

{{Short description|Pattern of romantic or sexual attraction}}
{{redirect|Sexual preference|the book|Sexual Preference (book){{!}}''Sexual Preference'' (book)}}
{{pp-pc|small=yes}}
{{sexual orientation}}
'''Sexual orientation''' is an enduring personal pattern of [[Romance (love)|romantic]] attraction or [[sexual attraction]] (or a combination of these) to persons of the opposite [[sex]] or [[gender]], the same sex or gender, or to both sexes or more than one gender.<!-- NOTE: "Sex" and "gender" are not always the same thing; for example, "sex" may refer to "biological sex" (being male or female), while "gender" may refer to a person's identity of being a man or a woman; therefore, like the Heterosexuality, Homosexuality and Bisexuality articles, we have included both in the lead. Also, see the third source for this paragraph.--> Patterns are generally categorized under [[heterosexuality]], [[homosexuality]], and [[bisexuality]],<ref name="AmPsycholAssn-whatis">{{cite web|title=Sexual Orientation & Homosexuality|publisher=[[American Psychological Association]]|date=2020|access-date=February 6, 2020|url=https://www.apa.org/topics/lgbt/orientation|archive-date=February 16, 2019|archive-url=https://web.archive.org/web/20190216213126/https://www.apa.org/topics/lgbt/orientation|url-status=live}}</ref><ref name="AmPsychiAssn-Sexual orientation">{{Cite web|title=Sexual Orientation|publisher=[[American Psychiatric Association]]|access-date=January 1, 2013|url=http://www.healthyminds.org/More-Info-For/GayLesbianBisexuals.aspx|archive-date=July 22, 2011|archive-url=https://web.archive.org/web/20110722080052/http://www.healthyminds.org/More-Info-For/GayLesbianBisexuals.aspx}}</ref><ref name="AmPsycholAssn-definitions">{{cite web |date=2015 |title=Definitions Related to Sexual Orientation and Gender Diversity in APA Documents |url=https://www.apa.org/pi/lgbt/resources/sexuality-definitions.pdf |archive-url=https://web.archive.org/web/20210122054116/https://www.apa.org/pi/lgbt/resources/sexuality-definitions.pdf |archive-date=January 22, 2021 |access-date=February 6, 2020 |publisher=[[American Psychological Association]] |page=6 |quote=Sexual orientation refers to the sex of those to whom one is sexually and romantically attracted. [...] [It is] one's enduring sexual attraction to male partners, female partners, or both. Sexual orientation may be heterosexual, same-sex (gay or lesbian), or bisexual. [...] A person may be attracted to men, women, both, neither, or to people who are genderqueer, androgynous, or have other gender identities. Individuals may identify as lesbian, gay, heterosexual, bisexual, queer, pansexual, or asexual, among others. [...] Categories of sexual orientation typically have included attraction to members of one's own sex (gay men or lesbians), attraction to members of the other sex (heterosexuals), and attraction to members of both sexes (bisexuals). While these categories continue to be widely used, research has suggested that sexual orientation does not always appear in such definable categories and instead occurs on a continuum [...]. Some people identify as pansexual or queer in terms of their sexual orientation, which means they define their sexual orientation outside of the gender binary of 'male' and 'female' only.}}</ref> while [[asexuality]] (experiencing no sexual attraction to others) is sometimes<!-- NOTE: "Sometimes" is correct. Sources are clear about how sexual orientation is typically conceptualized. It is typically conceptualized as heterosexuality, homosexuality, and bisexuality. Asexuality, although termed (and treated as) a sexual orientation in some sources, is debated as one among researchers. And to some of them, it is a lack of a sexual orientation.--> identified as the fourth category.<ref name="Sex and society">{{cite book|title=Sex and Society|volume=2|pages=82–83|isbn=978-0-7614-7905-5|publisher=[[Marshall Cavendish]]|year=2009|editor=Marshall Cavendish Corporation|contribution=Asexuality|access-date=February 2, 2013|url=https://books.google.com/books?id=aVDZchwkIMEC&pg=PA82|archive-date=October 16, 2015|archive-url=https://web.archive.org/web/20151016040824/https://books.google.com/books?id=aVDZchwkIMEC&pg=PA82|url-status=live}}</ref><ref name="Bogaert">{{cite journal|vauthors=Bogaert, AF|title= Asexuality: What It Is and Why It Matters|journal=[[The Journal of Sex Research]]|volume= 52|date=April 2015 |pmid=25897566|doi=10.1080/00224499.2015.1015713|issue=4|pages=362–379|s2cid= 23720993}}</ref>

These categories are aspects of the more nuanced nature of [[sexual identity]] and terminology.<ref name="AmPsycholAssn-definitions"/> For example, people may use other [[Label (sociology)|labels]], such as ''[[Pansexuality|pansexual]]'' or ''[[Polysexuality|polysexual]]'',<ref name="AmPsycholAssn-definitions"/><ref name="Firestein">{{cite book| first = Beth A.| last = Firestein| title = Becoming Visible: Counseling Bisexuals Across the Lifespan| publisher = [[Columbia University Press]]| page = 9| year = 2007| access-date = October 3, 2012| isbn = 978-0-231-13724-9| url = https://books.google.com/books?id=1pCKkZmBU1EC&pg=PA9| archive-date = February 4, 2021| archive-url = https://web.archive.org/web/20210204020834/https://books.google.com/books?id=1pCKkZmBU1EC&pg=PA9| url-status = live}}</ref> or none at all.<ref name="AmPsycholAssn-whatis" /> According to the [[American Psychological Association]], sexual orientation "also refers to a person's sense of identity based on those attractions, related behaviors, and membership in a community of others who share those attractions".<ref name="AmPsycholAssn-whatis" /><ref name="Calif-amici">{{cite web|url=http://www.courts.ca.gov/documents/Amer_Psychological_Assn_Amicus_Curiae_Brief.pdf|page=30|title=Case No. S147999 in the Supreme Court of the State of California, In re Marriage Cases Judicial Council Coordination Proceeding No. 4365(...) – APA California Amicus Brief&nbsp;— As Filed|others=p. 33 n. 60 (p. 55 per Adobe Acrobat Reader);citation per ''id.'', Brief, p. 6 n. 4 (p. 28 per Adobe Acrobat Reader).|access-date=March 13, 2013|archive-date=January 18, 2012|archive-url=https://web.archive.org/web/20120118184353/http://www.courts.ca.gov/documents/Amer_Psychological_Assn_Amicus_Curiae_Brief.pdf|url-status=live}}</ref> [[Androphilia and gynephilia|''Androphilia'' and ''gynephilia'']] are terms used in [[behavioral science]] to describe sexual orientation as an alternative to a [[gender binary]] conceptualization. ''Androphilia'' describes sexual attraction to [[masculinity]]; ''gynephilia'' describes the sexual attraction to [[femininity]].<ref name="schmidt2010">Schmidt J (2010). Migrating Genders: Westernisation, Migration, and Samoan Fa'afafine, p. 45 Ashgate Publishing, Ltd., {{ISBN|978-1-4094-0273-2}}</ref> The term ''sexual preference'' largely overlaps with sexual orientation, but is generally distinguished in psychological research.<ref name="Preference">{{cite news |title=Avoiding Heterosexual Bias in Language |publisher=[[American Psychological Association]] |url=http://www.colby.edu/psychology/APA/Gender.pdf |access-date=July 19, 2011 |archive-url=https://web.archive.org/web/20120813022744/http://www.colby.edu/psychology/APA/Gender.pdf |archive-date=August 13, 2012}}</ref> A person who identifies as bisexual, for example, may sexually prefer one sex over the other. ''Sexual preference'' may also suggest a degree of voluntary choice,<ref name="Preference" /><ref>{{cite book |title=The republic of choice: law, authority, and culture |last=Friedman |first=Lawrence Meir |year=1990 |publisher=Harvard University Press |isbn=978-0-674-76260-2 |page=92 |url=https://books.google.com/books?id=Z6iYwTFY5mIC&pg=PA92 |access-date=8 January 2012 |archive-date=17 February 2022 |archive-url=https://web.archive.org/web/20220217114727/https://books.google.com/books?id=Z6iYwTFY5mIC&pg=PA92 |url-status=live }}</ref><ref>{{cite book |title=Sexual revolutions: psychoanalysis, history and the father |last=Heuer |first=Gottfried |year=2011 |publisher=Taylor & Francis |isbn=978-0-415-57043-5 |page=49 |url=https://books.google.com/books?id=d3s_vH5YV-gC&pg=PA49 |access-date=8 January 2011 |archive-date=17 February 2022 |archive-url=https://web.archive.org/web/20220217114728/https://books.google.com/books?id=d3s_vH5YV-gC&pg=PA49 |url-status=live }}</ref> whereas sexual orientation is not a choice.<ref name="pediatrics2004">{{cite journal |author=Frankowski BL |author2=American Academy of Pediatrics Committee on Adolescence |date=June 2004 |title=Sexual orientation and adolescents |url=https://publications.aap.org/pediatrics/article-abstract/113/6/1827/64422/Sexual-Orientation-and-Adolescents?redirectedFrom=fulltext |journal=[[Pediatrics (journal)|Pediatrics]] |volume=113 |issue=6 |pages=1827–32 |doi=10.1542/peds.113.6.1827 |pmid=15173519 |archive-url=https://web.archive.org/web/20130320020943/http://pediatrics.aappublications.org/content/113/6/1827.long |archive-date=2013-03-20 |doi-access=|url-access=subscription }}</ref><ref name="Kersey-Matusiak">{{cite book|author=Gloria Kersey-Matusiak|url=https://books.google.com/books?id=X8O_wGedAYoC&pg=PA169|title=Delivering Culturally Competent Nursing Care|publisher=[[Springer Publishing Company]]|year=2012|isbn=978-0-8261-9381-0|page=169|quote=Most health and mental health organizations do not view sexual orientation as a 'choice.'|access-date=February 10, 2016|archive-date=November 30, 2016|archive-url=https://web.archive.org/web/20161130123356/https://books.google.com/books?id=X8O_wGedAYoC&pg=PA169|url-status=live}}</ref><ref name="Lamanna">{{cite book|last1=Lamanna|first1=Mary Ann|url=https://books.google.com/books?id=fofaAgAAQBAJ&pg=PA82|title=Marriages, Families, and Relationships: Making Choices in a Diverse Society|last2=Riedmann|first2=Agnes|last3=Stewart|first3=Susan D|publisher=[[Cengage Learning]]|year=2014|isbn=978-1-305-17689-8|page=82|quote=The reason some individuals develop a gay sexual identity has not been definitively established &nbsp;– nor do we yet understand the development of heterosexuality. The American Psychological Association (APA) takes the position that a variety of factors impact a person's sexuality. The most recent literature from the APA says that sexual orientation is not a choice that can be changed at will, and that sexual orientation is most likely the result of a complex interaction of environmental, cognitive and biological factors...is shaped at an early age...[and evidence suggests] biological, including genetic or inborn hormonal factors, play a significant role in a person's sexuality (American Psychological Association 2010).|access-date=February 11, 2016|archive-date=November 30, 2016|archive-url=https://web.archive.org/web/20161130141623/https://books.google.com/books?id=fofaAgAAQBAJ&pg=PA82|url-status=live}}</ref>

Although no single theory on the cause of sexual orientation has yet gained widespread support, scientists favor [[Biology and sexual orientation|biological theories]].<ref name="Bailey" /><ref name="pediatrics2004" /><ref name=":2">{{Cite journal |last1=Bogaert |first1=Anthony F. |last2=Skorska |first2=Malvina N. |date=2020-03-01 |title=A short review of biological research on the development of sexual orientation |journal=Hormones and Behavior |volume=119 |article-number=104659 |doi=10.1016/j.yhbeh.2019.104659 |issn=0018-506X |pmid=31911036 |doi-access=free}}</ref> There is considerably more evidence supporting nonsocial, biological causes of sexual orientation than social ones, especially for males.<ref name="Bailey" /><ref name="LeVay" /><ref name="Balthazart2">{{cite book |last=Balthazart |first=Jacques |url=https://books.google.com/books?id=3fjGjlcVINkC |title=The Biology of Homosexuality |date=2012 |publisher=Oxford University Press |isbn=978-0-19-983882-0 |access-date=27 July 2019 |archive-url=https://web.archive.org/web/20210126132532/https://books.google.com/books?id=3fjGjlcVINkC |archive-date=26 January 2021 |url-status=live}}</ref> A major hypothesis implicates the [[Prenatal development|prenatal environment]], specifically the organizational effects of hormones on the fetal brain.<ref name="Bailey" /><ref name=":2" /> There is no substantive evidence which suggests parenting or early childhood experiences play a role in developing a sexual orientation.<ref name="Bailey" /><ref name="rcp20072">{{cite web |title=Submission to the Church of England's Listening Exercise on Human Sexuality |url=http://www.rcpsych.ac.uk/workinpsychiatry/specialinterestgroups/gaylesbian/submissiontothecofe.aspx |url-status=live |archive-url=https://web.archive.org/web/20151016040825/http://www.rcpsych.ac.uk/workinpsychiatry/specialinterestgroups/gaylesbian/submissiontothecofe.aspx |archive-date=16 October 2015 |access-date=13 June 2013 |publisher=The Royal College of Psychiatrists}}</ref> Across cultures, most people are heterosexual, with a minority of people having a homosexual or bisexual orientation.<ref name="Bailey" /><ref name="LeVay">{{cite book |last=LeVay |first=Simon |url=https://archive.org/details/gaystraightreaso0000leva_e5c2/mode/1up?view=theater |title=Gay, Straight, and the Reason Why: The Science of Sexual Orientation |date=2017 |publisher=Oxford University Press |isbn=978-0-19-975296-6 |ol=26246092M |url-access=registration |via=[[Open Library]] |ol-access=free}}</ref>{{rp|8}}<ref name="Balthazart">{{cite book |last=Balthazart |first=Jacques |url=https://archive.org/details/biologyofhomosex0000balt/mode/1up |title=The Biology of Homosexuality |date=2012 |publisher=Oxford University Press |isbn=978-0-19-983882-0 |ol=16142775W |url-access=registration |via=[[Open Library]] |ol-access=free}}</ref>{{rp|9–10}} A person's sexual orientation can be anywhere on [[heterosexual-homosexual continuum|a continuum]], from exclusive attraction to the opposite sex to exclusive attraction to the same sex.<ref name="AmPsycholAssn-whatis" />

Sexual orientation is studied primarily within [[biology]], [[anthropology]], and [[psychology]] (including [[sexology]]), but it is also a subject area in [[sociology]], [[history]] (including [[social constructionism|social constructionist]] perspectives), and [[law]].<ref name=Cruz>{{cite journal|last1=Cruz|first1=David B.|title=Controlling Desires: Sexual Orientation Conversion and the Limits of Knowledge and Law|journal=Southern California Law Review|date=1999|volume=72|issue=5|pages=1297–400|pmid=12731502|url=http://www-bcf.usc.edu/~usclrev/pdf/072502.pdf|access-date=2015-05-21|archive-url=https://web.archive.org/web/20170919071205/http://www-bcf.usc.edu/~usclrev/pdf/072502.pdf|archive-date=2017-09-19}}</ref>

== Definitions and distinguishing from sexual identity and behavior ==

===General===
{{See also|Sexual identity|Human sexual activity|Situational sexual behavior}}

Sexual orientation is traditionally defined as including [[heterosexuality]], [[bisexuality]], and [[homosexual orientation|homosexuality]], while [[asexuality]] is considered the fourth category of sexual orientation by some researchers and has been defined as the absence of a traditional sexual orientation. An asexual has little to no sexual attraction to people.<ref name="Sex and society"/><ref name="Bogaert"/> It may be considered a lack of a sexual orientation,<ref name="Bogaert2004">{{cite journal|last1=Bogaert|first1=Anthony F.|author-link1=Anthony Bogaert|year=2004|title=Asexuality: prevalence and associated factors in a national probability sample|journal=Journal of Sex Research|volume=41|issue=3|pages=279–87|doi=10.1080/00224490409552235|pmid=15497056|s2cid=41057104}}</ref> and there is significant debate over whether or not it is a sexual orientation.<ref name="Sex and society"/><ref name="Bogaert"/>

Most definitions of sexual orientation include a psychological component, such as the direction of an individual's erotic desires, or a behavioral component, which focuses on the sex of the individual's sexual partners. Some people prefer simply to follow an individual's self-definition or [[Identity (social science)|identity]]. Scientific and professional understanding is that "the core attractions that form the basis for adult sexual orientation typically emerge between middle childhood and early adolescence".<ref name="AmPsycholAssn-whatis" /> Sexual orientation differs from sexual identity in that it encompasses relationships with others, while sexual identity is a concept of self.

The [[American Psychological Association]] states that "[s]exual orientation refers to an enduring pattern of emotional, romantic, and/or sexual attractions to men, women, or both sexes" and that "[t]his range of behaviors and attractions has been described in various cultures and nations throughout the world. Many cultures use identity labels to describe people who express these attractions. In the United States, the most frequent labels are [[lesbian]]s (women attracted to women), [[gay men]] (men attracted to men), and [[bisexuals]] (people attracted to both sexes). However, some people may use different labels or none at all". They additionally state that sexual orientation "is distinct from other components of sex and gender, including biological sex (the anatomical, physiological, and genetic characteristics associated with being male or female), gender identity (the psychological sense of being male or female), and social gender role (the cultural norms that define feminine and masculine behavior)".<ref name="AmPsycholAssn-whatis" />

Sexual identity and [[Human sexual activity|sexual behavior]] are closely related to sexual orientation, but they are distinguished, with sexual identity referring to an individual's conception of themselves, behavior referring to actual sexual acts performed by the individual, and orientation referring to "fantasies, attachments and longings."<ref>{{cite journal |author=Reiter L. |title=Sexual orientation, sexual identity, and the question of choice |journal=Clinical Social Work Journal |volume=17 |issue=2 |pages=138–50 |year=1989 |doi=10.1007/bf00756141|s2cid=144530462 }}</ref> Individuals may or may not express their sexual orientation in their behaviors.<ref name="AmPsycholAssn-whatis" /> People who have a [[non-heterosexual]] sexual orientation that does not align with their sexual identity are sometimes referred to as '[[closeted]]'. The term may, however, reflect a certain cultural context and particular stage of transition in societies which are gradually dealing with integrating sexual minorities. In studies related to sexual orientation, when dealing with the degree to which a person's [[sexual attraction]]s, behaviors and identity match, scientists usually use the terms ''concordance'' or ''discordance''. Thus, a woman who is attracted to other women, but calls herself heterosexual and only has sexual relations with men, can be said to experience discordance between her sexual orientation (homosexual or lesbian) and her sexual identity and behaviors (heterosexual).<ref name="Concordance/discordance in SO" />

''Sexual identity'' may also be used to describe a person's perception of their own ''sex'', rather than sexual orientation. The term ''sexual preference'' has a similar meaning to ''sexual orientation'', and the two terms are often used interchangeably, but the American Psychological Association states ''sexual preference'' suggests a degree of voluntary choice.<ref name="Preference" /> The term has been listed by the American Psychological Association's Committee on Gay and Lesbian Concerns as a wording that advances a "heterosexual bias".<ref name="Preference" /> The term ''sexual orientation'' was introduced by [[sexologist]] [[John Money]] in place of ''sexual preference'', arguing that attraction is not necessarily a matter of free choice.<ref name="John Money, Ph.D">{{cite journal|last1=Ehrhardt|first1=Anke A.|title=John Money, Ph.D.|journal=The Journal of Sex Research|date=August 2007|volume=44|issue=3|pages=223–224|jstor=20620298|doi=10.1080/00224490701580741|pmid=3050136|s2cid=147344556}}</ref>

===Androphilia, gynephilia, and other terms===
{{Main|Androphilia and gynephilia}}
{{See also|Attraction to transgender people}}

''Androphilia'' and ''gynephilia'' (or ''gynecophilia'') are terms used in behavioral science to describe sexual attraction, as an alternative to a homosexual and heterosexual conceptualization. They are used for identifying a subject's object of attraction without attributing a [[sex assignment]] or [[gender identity]] to the subject. Related terms such as ''[[Pansexuality|pansexual]]'' and ''[[Polysexuality|polysexual]]'' do not make any such assignations to the subject.<ref name="Firestein" /><ref name="Sex and society2">{{cite book|title=Sex and Society|volume=2|page=593|last=Rice|first=Kim|isbn=978-0-7614-7905-5|publisher=[[Marshall Cavendish]]|year=2009|editor=Marshall Cavendish Corporation|contribution=Pansexuality|access-date=October 3, 2012|url=https://books.google.com/books?id=YtsxeWE7VD0C&q=Pansexuality&pg=PA593|archive-date=November 13, 2020|archive-url=https://web.archive.org/web/20201113100728/https://books.google.com/books?id=YtsxeWE7VD0C&q=Pansexuality&pg=PA593|url-status=live}}</ref> People may also use terms such as ''[[queer]]'', ''pansensual,'' ''[[polyfidelitous]],'' ''ambisexual,'' or personalized identities such as ''byke'' or ''biphilic''.<ref name="Firestein" />

Using ''androphilia'' and ''gynephilia'' can avoid confusion and offense when describing people in non-western cultures, as well as when describing intersex and transgender people. Psychiatrist [[Anil Aggrawal]] explains that androphilia, along with gynephilia,<ref name="Aggrawal2008">Aggrawal, Anil (2008). ''Forensic and medico-legal aspects of sexual crimes and unusual sexual practices.'' CRC Press, {{ISBN|978-1-4200-4308-2}}</ref>{{Page needed|date=August 2021}}<blockquote>is needed to overcome immense difficulties in characterizing the sexual orientation of trans men and trans women. For instance, it is difficult to decide whether a trans man erotically attracted to males is a heterosexual female or a homosexual male; or a trans woman erotically attracted to females is a heterosexual male or a lesbian female. Any attempt to classify them may not only cause confusion but arouse offense among the affected subjects. In such cases, while defining sexual attraction, it is best to focus on the object of their attraction rather than on the sex or gender of the subject.</blockquote>Sexologist [[Milton Diamond]] writes, "The terms heterosexual, homosexual, and bisexual are better used as adjectives, not nouns, and are better applied to behaviors, not people. This usage is particularly advantageous when discussing the partners of transsexual or intersexed individuals. These newer terms also do not carry the social weight of the former ones."<ref name="diamond2010">Diamond M (2010). Sexual orientation and gender identity. In Weiner IB, Craighead EW eds. ''[[iarchive:corsiniencyclope0004unse/page/1578/mode/2up|The Corsini Encyclopedia of Psychology]]'', Volume 4.  p. 1578. John Wiley and Sons,  {{ISBN|978-0-470-17023-6}}</ref>

Some researchers advocate use of the terminology to avoid [[bias]] inherent in [[Western culture|Western]] conceptualizations of human sexuality. Writing about the [[Samoa]]n ''[[fa'afafine]]'' demographic, sociologist Johanna Schmidt writes that in cultures where a [[third gender]] is recognized, a term like "homosexual transsexual" does not align with cultural categories.<ref name="schmidt2001">Schmidt J (2001). [http://wwwsshe.murdoch.edu.au/intersections/issue6/schmidt.html Redefining fa'afafine: Western discourses and the construction of transgenderism in Samoa.] {{Webarchive|url=https://web.archive.org/web/20080322034626/http://wwwsshe.murdoch.edu.au/intersections/issue6/schmidt.html |date=2008-03-22 }} ''Intersections: Gender, history and culture in the Asian context''</ref>

Some researchers, such as [[Bruce Bagemihl]], have criticized certain ways the labels "heterosexual" and "homosexual" have been used for transgender people, writing, "...the point of reference for 'heterosexual' or 'homosexual' orientation in this nomenclature is solely the individual's genetic sex prior to reassignment (see for example, Blanchard et al. 1987, Coleman and Bockting, 1988, Blanchard, 1989). These labels thereby ignore the individual's personal sense of gender identity taking precedence over biological sex, rather than the other way around." Bagemihl goes on to take issue with the way this terminology makes it easy to claim transsexuals are really homosexual males seeking to escape from stigma.<ref name="bagemihl">Bagemihl B. Surrogate phonology and transsexual faggotry: A linguistic analogy for uncoupling sexual orientation from gender identity. In ''Queerly Phrased: Language, Gender, and Sexuality''. Anna Livia, Kira Hall (eds.) pp. 380 ff. Oxford University Press {{ISBN|0-19-510471-4}}</ref>

Terms have been proposed for sexual attraction to a [[Assigned male at birth|person born male]] with a feminine gender expression, including ''gynandromorphophilia'' (adjective: ''gynandromorphophilic'')<ref name="Blaney-Krueger2014" /><ref name=Patterson-2020>{{cite thesis |last=Petterson |first=Lanna J |title=Male sexual orientation: a cross-cultural perspective |website=OPUS: Open Uleth Scholarship |date=2020 |url=https://hdl.handle.net/10133/5763 |type=thesis |location=Lethbridge, Alberta |page=iii, 1–276|hdl=10133/5763 }}</ref> and ''gynemimetophilia'' (adj.: ''gynemimetophilic'').<ref name=Money-Lamacz-1984>{{cite journal |first1=John |last1=Money |first2=Margaret |last2=Lamacz |title=Gynemimesis and gynemimetophilia: Individual and cross-cultural manifestations of a gender-coping strategy hitherto unnamed |journal=Comprehensive Psychiatry |volume=25 |issue=4 |year=1984 |pages=392–403 |issn=0010-440X |publisher=Elsevier |doi=10.1016/0010-440X(84)90074-9 |pmid=6467919 }}</ref><ref name="Blaney-Krueger2014">{{cite book |last1=Blaney |first1=Paul H. |last2=Krueger |first2=Robert F. |last3=Millon |first3=Theodore |title=Oxford Textbook of Psychopathology |url=https://books.google.com/books?id=VoEZBAAAQBAJ&pg=PA592 |date=19 September 2014 |edition=3rd |publisher=Oxford University Press |location=New York |isbn=978-0-19-981177-9 |pages=592– |oclc=900980099 |access-date=6 March 2021 |archive-date=11 May 2021 |archive-url=https://web.archive.org/web/20210511080008/https://books.google.com/books?id=VoEZBAAAQBAJ&pg=PA592 |url-status=live }}</ref>

=== Gender, transgender, cisgender, and conformance ===
{{Original research section|date=August 2021}}[[File:Kathoy1649.jpg|thumb|240px|[[Kathoey|Katheoys]] in Thailand]]
The earliest writers on sexual orientation usually understood it to be intrinsically linked to the subject's own sex. For example, it was thought that a typical female-bodied person who is attracted to female-bodied persons would have masculine attributes, and vice versa.<ref>{{cite journal |author=Minton HL |title=Femininity in men and masculinity in women: American psychiatry and psychology portray homosexuality in the 1930s |journal=[[Journal of Homosexuality]] |volume=13 |issue=1 |pages=1–21 |year=1986 |pmid=3534080 |doi=10.1300/J082v13n01_01}}<br />Terry, J. (1999). ''An American obsession: Science, medicine, and homosexuality in modern society.'' Chicago: University of Chicago Press</ref> This understanding was shared by most of the significant theorists of sexual orientation from the mid nineteenth to early twentieth century, such as [[Karl Heinrich Ulrichs]], [[Richard von Krafft-Ebing]], [[Magnus Hirschfeld]], [[Havelock Ellis]], [[Carl Jung]], and [[Sigmund Freud]], as well as many gender-variant homosexual people themselves. However, this understanding of homosexuality as sexual inversion was disputed at the time, and, through the second half of the twentieth century, [[gender identity]] came to be increasingly seen as a phenomenon distinct from sexual orientation. [[Transgender]] and [[cisgender]] people may be attracted to men, women, or both, although the prevalence of different sexual orientations is quite different in these two populations. An individual homosexual, heterosexual, or bisexual person may be masculine, feminine, or [[Androgyny|androgynous]]. Nevertheless, an analysis by [[J. Michael Bailey]] and [[Kenneth Zucker]] found a majority of the gay men and lesbians [[Sample (statistics)|sampled]] in multiple studies reported "substantially more" cross-sex-typed behavior in childhood than heterosexual subjects.<ref>{{cite journal |author=[[J. Michael Bailey|Bailey JM]], Zucker KJ |title=Childhood sex-typed behavior and sexual orientation: a conceptual analysis and quantitative review |journal=Developmental Psychology |volume=31 |issue=1 |pages=43–55 |year=1995 |doi=10.1037/0012-1649.31.1.43 |s2cid=28174284 |url=https://faculty.wcas.northwestern.edu/JMichael-Bailey/Publications/Bailey%20%26%20Zucker%2C%201995.pdf |access-date=2022-08-05 |archive-date=2022-01-23 |archive-url=https://web.archive.org/web/20220123000118/https://faculty.wcas.northwestern.edu/JMichael-Bailey/Publications/Bailey%20%26%20Zucker%2C%201995.pdf |url-status=live }}</ref>

Sexual orientation sees greater intricacy when non-binary understandings of both [[sex]] and [[gender]] are considered. Sociologist [[Paula Rodriguez Rust]] (2000) argues for a more multifaceted definition of sexual orientation:

{{quotation|Most alternative models of sexuality... define sexual orientation in terms of [[dichotomy|dichotomous]] biological sex or gender... Most theorists would not eliminate the reference to sex or gender, but instead advocate incorporating more complex nonbinary concepts of sex or gender, more complex relationships between sex, gender, and sexuality, and/or additional nongendered dimensions into models of sexuality.<ref>[[Paula Rodriguez Rust|Rodriguez Rust, Paula C.]] ''Bisexuality: A contemporary paradox for women'', Journal of Social Issues, vol. 56(2), Summer 2000, pp. 205–21. Special Issue: Women's sexualities: New perspectives on sexual orientation and gender. [https://docplayer.net/43268398-Bisexuality-a-contemporary-paradox-for-women.html Article online.] {{void|Fabrickator|comment|link to working archive of findarticles.com copy: https://web.archive.org/web/20070310220454/http://www.findarticles.com/p/articles/mi_m0341/is_2_56/ai_66419862/pg_2 |date=2007-03-10}}<br />Also published in: Rodriguez Rust, Paula C. ''Bisexuality in the United States: A Social Science Reader''. Columbia University Press, 2000. {{ISBN|0-231-10227-5}}.</ref>}}

=== Relationships outside of orientation ===
Gay and lesbian people can have sexual relationships with someone of the opposite sex for a variety of reasons, including the desire for a perceived traditional family and concerns of discrimination and religious [[ostracism]].<ref name="Brokeback">{{cite news|title=Many Couples Must Negotiate Terms of 'Brokeback' Marriages|url=https://www.nytimes.com/2006/03/07/health/07broke.html?_r=2&oref=slogin&oref=slogin|last=Butler|first=Katy|date=March 7, 2006|newspaper=New York Times|access-date=February 23, 2017|archive-date=December 24, 2018|archive-url=https://web.archive.org/web/20181224191941/https://www.nytimes.com/2006/03/07/health/many-couples-must-negotiate-terms-of-brokeback-marriages.html|url-status=live}}</ref><ref>{{cite news
 |title=How to tell if your husband is gay
 |first=Rochelle
 |last=Hentges
 |newspaper=[[Pittsburgh Tribune-Review]]
 |date=October 4, 2006
 |url=http://www.pittsburghlive.com/x/pittsburghtrib/news/tribpm/s_473458.html
 |archive-url=https://web.archive.org/web/20061022161748/http://www.pittsburghlive.com/x/pittsburghtrib/news/tribpm/s_473458.html
 |archive-date=October 22, 2006
}}</ref><ref>{{Cite journal|title=Taylor & Francis Online: Gay Men from Heterosexual Marriages |journal=Journal of Homosexuality|volume=42|issue=4|pages=15–34|date=30 June 2012|doi=10.1300/J082v42n04_02|pmid=12243483|last1 = Higgins|first1 = Daryl J.|s2cid=32047519}}</ref><ref>{{citation |url= http://www.sltrib.com/faith/ci_4138478 |title= Gay, Mormon, married |first= Peggy Fletcher |last= Stack |author-link= Peggy Fletcher Stack |date= August 5, 2006 |newspaper= [[The Salt Lake Tribune]] |archive-url= https://web.archive.org/web/20130621165041/http://www.sltrib.com/faith/ci_4138478 |archive-date= June 21, 2013 }}</ref><ref>{{cite web|url=http://psychologytoday.com/articles/pto-19990301-000030.html|archive-url=https://archive.today/20070501170741/http://psychologytoday.com/articles/pto-19990301-000030.html|archive-date=2007-05-01|title=Gay No More|work=psychologytoday.com}}</ref> While some [[LGBTQ]] people hide their respective orientations from their spouses, others develop positive gay and lesbian identities while maintaining successful heterosexual [[marriage]]s.<ref>{{cite journal |author1=Hays D |author2=Samuels A |title=Heterosexual women's perceptions of their marriages to bisexual or homosexual men |journal=J Homosex |volume=18 |issue=1–2 |pages=81–100 |year=1989 |pmid=2794500 |doi=10.1300/J082v18n01_04 }}</ref><ref>{{cite journal |author=Coleman E |title=Bisexual and gay men in heterosexual marriage: conflicts and resolutions in therapy |journal=J Homosex |volume=7 |issue=2–3 |pages=93–103 |year=1981 |pmid=7346553 |doi=10.1300/J082v07n02_11 }}</ref><ref>{{cite journal |author=Matteson DR |title=Bisexual men in marriage: is a positive homosexual identity and stable marriage possible? |journal=J Homosex |volume=11 |issue=1–2 |pages=149–71 |year=1985 |pmid=4056386 |doi=10.1300/J082v11n01_12}}</ref> [[Coming out]] of the closet to oneself, a spouse of the opposite sex, and children can present challenges that are not faced by gay and lesbian people who are not married to people of the opposite sex or do not have children.<ref>{{Cite journal|last1=Nascimento|first1=Geysa Cristina Marcelino|last2=Scorsolini-Comin|first2=Fabio|last3=Nascimento|first3=Geysa Cristina Marcelino|last4=Scorsolini-Comin|first4=Fabio|date=September 2018|title=Revealing one's Homosexuality to the Family: An Integrative Review of the Scientific Literature|journal=Trends in Psychology|language=en|volume=26|issue=3|pages=1527–1541|doi=10.9788/tp2018.3-14pt|issn=2358-1883|doi-access=free}}</ref>

=== Fluidity ===
{{Main|Sexual fluidity}}Often, sexual orientation and [[sexual orientation identity]] are not distinguished, which can impact accurately assessing sexual identity and whether or not sexual orientation is able to change; sexual orientation identity can change throughout an individual's life, and may or may not align with biological sex, sexual behavior, or actual sexual orientation.<ref name="Sinclair">Sinclair, Karen, About Whoever: The Social Imprint on Identity and Orientation, NY, 2013 {{ISBN|9780981450513}}</ref><ref name="Concordance/discordance in SO">{{cite journal|first=Michael W.|last=Ross|author2=Essien, E. James |author3=Williams, Mark L. |author4= Fernandez-Esquer, Maria Eugenia. |title=Concordance Between Sexual Behavior and Sexual Identity in Street Outreach Samples of Four Racial/Ethnic Groups|publisher=American Sexually Transmitted Diseases Association|year=2003|pmid=12567166|journal=Sexually Transmitted Diseases|volume=30|issue=2|pages=110–113|doi=10.1097/00007435-200302000-00003|s2cid=21881268|doi-access=free}}</ref> Sexual orientation is stable and unchanging for the vast majority of people, but some research indicates that some people may experience change in their sexual orientation, and this is more likely for women than for men.<ref name=fluidity>*{{cite journal|last1=Bailey|first1=J. Michael|last2=Vasey|first2=Paul|last3=Diamond|first3=Lisa|author4-link=Marc Breedlove|last4=Breedlove|first4=S. Marc|last5=Vilain|first5=Eric|last6=Epprecht|first6=Marc|title=Sexual Orientation, Controversy, and Science|journal=Psychological Science in the Public Interest|date=2016|volume=17|issue=2|pages=45–101|doi=10.1177/1529100616637616|pmid=27113562|url=https://www.researchgate.net/publication/301639075|quote=Sexual fluidity is situation-dependent flexibility in a person's sexual responsiveness, which makes it possible for some individuals to experience desires for either men or women under certain circumstances regardless of their overall sexual orientation....We expect that in all cultures the vast majority of individuals are sexually predisposed exclusively to the other sex (i.e., heterosexual) and that only a minority of individuals are sexually predisposed (whether exclusively or non-exclusively) to the same sex.|doi-access=free|access-date=2019-09-29|archive-date=2020-06-11|archive-url=https://web.archive.org/web/20200611031054/https://www.researchgate.net/publication/301639075|url-status=live}}
*{{cite book|author1=Dennis Coon|author2=John O. Mitterer|title=Introduction to Psychology: Gateways to Mind and Behavior with Concept Maps and Reviews|publisher=[[Cengage Learning]]|isbn=978-1-111-83363-3|year=2012|page=372|access-date=February 18, 2016|url=https://books.google.com/books?id=EYwjCQAAQBAJ&pg=PA372|quote=Sexual orientation is a deep part of personal identity and is usually quite stable. Starting with their earliest erotic feelings, most people remember being attracted to either the opposite sex or the same sex. [...] The fact that sexual orientation is usually quite stable doesn't rule out the possibility that for some people sexual behavior may change during the course of a lifetime.}}
*{{cite book|author1=Eric Anderson|author2=Mark McCormack|title=The Changing Dynamics of Bisexual Men's Lives|chapter=Measuring and Surveying Bisexuality|publisher=[[Springer Science & Business Media]]|isbn=978-3-319-29412-4|year=2016|page=47|access-date=June 22, 2019|chapter-url=https://books.google.com/books?id=7_AgDAAAQBAJ&pg=PA47|quote=[R]esearch suggests that women's sexual orientation is slightly more likely to change than men's (Baumeister 2000; Kinnish et al. 2005). The notion that sexual orientation can change over time is known as ''sexual fluidity''. Even if sexual fluidity exists for some women, it does not mean that the majority of women will change sexual orientations as they age – rather, sexuality is stable over time for the majority of people.|archive-date=August 24, 2021|archive-url=https://web.archive.org/web/20210824071645/https://books.google.com/books?id=7_AgDAAAQBAJ&pg=PA47|url-status=live}}</ref> The American Psychological Association distinguishes between sexual orientation (an innate attraction) and sexual orientation identity (which may change at any point in a person's life).<ref name=apa2009-2>{{cite web|title=Appropriate Therapeutic Responses to Sexual Orientation|publisher=[[American Psychological Association]]|pages=63, 86|date=2009|access-date=February 3, 2015|url=http://www.apa.org/pi/lgbc/publications/therapeutic-response.pdf|archive-date=June 3, 2013|archive-url=https://web.archive.org/web/20130603121635/http://www.apa.org/pi/lgbc/publications/therapeutic-response.pdf|url-status=live}}</ref>

== Causes ==

The exact causes for the development of a particular sexual orientation have yet to be established. To date, much research has been conducted to determine the influence of genetics, hormonal action, development dynamics, social and cultural influences—which has led many to think that biology and environment factors play a complex role in forming it.<ref name="pediatrics2004" /><ref name="Kersey-Matusiak" /><ref name="Lamanna" />

=== Biology ===

{{Main|Biology and sexual orientation}}

Research has identified several biological factors which may be related to the development of sexual orientation, including [[gene]]s, [[Prenatal hormones and sexual orientation|prenatal hormones]], and [[Human brain|brain]] structure. No single controlling cause has been identified, and research is continuing in this area.<ref name="twin-adol">{{cite journal|last2=Bruckner|first2=H.|year=2001|title=Opposite-sex twins and adolescent same-sex attraction|url=http://iserp.columbia.edu/sites/default/files/working_papers/2001_04.pdf|journal=American Journal of Sociology|volume=107|issue=5|pages=1179–205|doi=10.1086/341906|last1=Bearman|first1=P.S.|archive-url=https://web.archive.org/web/20121220235217/http://iserp.columbia.edu/sites/default/files/working_papers/2001_04.pdf|archive-date=2012-12-20|citeseerx=10.1.1.483.4722|s2cid=13094910}}</ref>

Although researchers generally believe that sexual orientation is not determined by any one factor but by a combination of genetic, hormonal, and environmental influences,<ref name="pediatrics2004" /><ref name="Lamanna" /><ref name="Stuart">{{cite book |author=Gail Wiscarz Stuart |url=https://books.google.com/books?id=ivALBAAAQBAJ&pg=PA502 |title=Principles and Practice of Psychiatric Nursing |publisher=[[Elsevier Health Sciences]] |year=2014 |isbn=978-0-323-29412-6 |page=502 |quote=No conclusive evidence supports any one specific cause of homosexuality; however, most researchers agree that biological and social factors influence the development of sexual orientation. |access-date=February 11, 2016 |archive-url=https://web.archive.org/web/20161130185850/https://books.google.com/books?id=ivALBAAAQBAJ&pg=PA502 |archive-date=November 30, 2016 |url-status=live}}</ref> with biological factors involving a complex interplay of genetic factors and the early uterine environment,<ref name="Lamanna" /><ref name="rcp2007">{{cite web |title=Submission to the Church of England's Listening Exercise on Human Sexuality |url=http://www.rcpsych.ac.uk/workinpsychiatry/specialinterestgroups/gaylesbian/submissiontothecofe/psychiatryandlgbpeople.aspx#history |archive-url=https://web.archive.org/web/20140218210240/http://www.rcpsych.ac.uk/workinpsychiatry/specialinterestgroups/gaylesbian/submissiontothecofe/psychiatryandlgbpeople.aspx |archive-date=February 18, 2014 |access-date=13 June 2013 |publisher=The Royal College of Psychiatrists}}</ref> they favor biological models for the cause.<ref name="pediatrics2004" /> There is considerably more evidence supporting nonsocial, biological causes of sexual orientation than social ones, especially for males.<ref name="Bailey" /> Scientists do not believe that sexual orientation is a choice,<ref name="pediatrics2004" /><ref name="Kersey-Matusiak" /><ref name="Lamanna" /> and some of them believe that it is established at conception.<ref name="Vare">Vare, Jonatha W., and Terry L. Norton. "Understanding Gay and Lesbian Youth: Sticks, Stones and Silence." Cleaning House 71.6 (1998): 327–31: Education Full Text (H.W. Wilson). Web. 19 April 2012.</ref> Current scientific investigation usually seeks to find biological explanations for the adoption of a particular sexual orientation.<ref name="pediatrics2004" /> Scientific studies have found a number of statistical [[Biology and sexual orientation#Biological differences in gay men and lesbian women|biological differences between gay people and heterosexuals]], which may result from the same underlying cause as sexual orientation itself.<ref>{{cite web |last1=Rahman |first1=Qazi |title='Gay genes': science is on the right track, we're born this way. Let's deal with it. |url=https://www.theguardian.com/science/blog/2015/jul/24/gay-genes-science-is-on-the-right-track-were-born-this-way-lets-deal-with-it |work=The Guardian |date=24 July 2015 |access-date=3 January 2020 |archive-date=16 August 2021 |archive-url=https://web.archive.org/web/20210816181957/https://www.theguardian.com/science/blog/2015/jul/24/gay-genes-science-is-on-the-right-track-were-born-this-way-lets-deal-with-it |url-status=live }}</ref>

==== Genetic factors ====

[[Gene]]s may be related to the development of sexual orientation. A twin study from 2001 appears to exclude genes as a major factor,<ref name="twin-adol" /> while a twin study from 2010 found that homosexuality was explained by both genes and environmental factors.<ref>{{Cite journal|last1=Långström|first1=Niklas|last2=Rahman|first2=Qazi|last3=Carlström|first3=Eva|last4=Lichtenstein|first4=Paul|date=2010-02-01|title=Genetic and Environmental Effects on Same-sex Sexual Behavior: A Population Study of Twins in Sweden|journal=Archives of Sexual Behavior|language=en|volume=39|issue=1|pages=75–80|doi=10.1007/s10508-008-9386-1|issn=0004-0002|pmid=18536986|s2cid=11870487}}</ref> However, [[experimental design]] of the available twin studies has made their interpretation difficult.

In 2012, a large, comprehensive&nbsp;[[Genome-wide association study|genome-wide linkage study]]&nbsp;of male sexual orientation was conducted by several independent groups of researchers. Significant linkage to homosexuality was found with genes on chromosome [[Xq28]] and chromosome 8 in the pericentromeric region. The authors concluded that "our findings, taken in context with previous work, suggest that genetic variation in each of these regions contributes to development of the important psychological trait of male sexual orientation." It was the largest study of the genetic basis of homosexuality to date and was published online in November 2014.<ref>{{cite journal|last1=Sanders|first1=A.R.|last2=Martin|first2=E.R.|last3=Beecham|first3=G.W.|last4=Guo|first4=S.|last5=Dawood|first5=K.|last6=Rieger|first6=G.|last7=Badner|first7=J.A.|last8=Gershon|first8=E.S.|last9=Krishnappa|first9=R.S.|last10=Kolundzija|first10=A.B.|last11=Duan|first11=J.|last12=Gejman|first12=P.V.|last13=Bailey|first13=J. M.|title=Genome-wide scan demonstrates significant linkage for male sexual orientation|journal=Psychological Medicine|date=17 November 2014|volume=45|issue=7|pages=1379–1388|doi=10.1017/S0033291714002451|pmid=25399360|s2cid=4027333 |s2cid-access=free |url=http://biology-web.nmsu.edu/~houde/Sanders%20et%20al%202014.pdf |archive-url=https://web.archive.org/web/20171031013213/http://biology-web.nmsu.edu/~houde/Sanders%20et%20al%202014.pdf |archive-date= Oct 31, 2017}}</ref>

However, in August 2019, a [[genome-wide association study]] of 493,001 individuals concluded that hundreds or thousands of genetic variants underlie homosexual behavior in both sexes, with 5 variants in particular being significantly associated. They stated that in contrast to linkage studies that found substantial association of sexual orientation with variants on the X-chromosome, they found no excess of signal (and no individual genome-wide significant variants) on Xq28 or the rest of the X chromosome.<ref>
*{{cite journal |last1=Zietsch |first1=Brendan P. |last2=Neale |first2=Benjamin M. |last3=Perry |first3=John R. B. |last4=Sanders |first4=Alan R. |last5=Martin |first5=Eden R. |last6=Beecham |first6=Gary W. |last7=Harris |first7=Kathleen Mullan |last8=Auton |first8=Adam |last9=Långström |first9=Niklas |last10=Lundström |first10=Sebastian |last11=Lichtenstein |first11=Paul |last12=((23andMe Research Team)) |last13=Sathirapongsasuti |first13=J. Fah |last14=Guo |first14=Shengru |last15=Abdellaoui |first15=Abdel |last16=Busch |first16=Alexander S. |last17=Wedow |first17=Robbee |last18=Maier |first18=Robert |last19=Nivard |first19=Michel G. |last20=Verweij |first20=Karin J. H. |last21=Ganna |first21=Andrea |title=Large-scale GWAS reveals insights into the genetic architecture of same-sex sexual behavior |journal=Science |date=30 August 2019 |volume=365 |issue=6456 |article-number=eaat7693 |doi=10.1126/science.aat7693 |pmid=31467194 |language=en |issn=0036-8075|pmc=7082777 |doi-access=free }}
*{{cite web |title=Genetics of Sexual Behavior |url=https://geneticsexbehavior.info/what-we-found/ |website=Genetics of Sexual Behavior |publisher=geneticsexbehavior.info |access-date=30 August 2019 |date=28 February 2018}}
*{{cite journal |last1=Lambert |first1=Jonathan |title=No 'gay gene': Massive study homes in on genetic basis of human sexuality |journal=Nature |volume=573 |issue=7772 |pages=14–15 |date=29 August 2019 |doi=10.1038/d41586-019-02585-6 |pmid=31481774 |language=en|bibcode=2019Natur.573...14L |doi-access=free }}</ref>

==== Hormones ====
{{Main|Prenatal hormones and sexual orientation}}

The hormonal theory of sexuality holds that just as exposure to certain hormones plays a role in fetal [[sex differentiation]], hormonal exposure also influences the sexual orientation that emerges later in the adult. Fetal hormones may be seen as either the primary influence upon adult sexual orientation or as a co-factor interacting with genes or environmental and social conditions.<ref name="BornGay-passim">Wilson, G., & Q. Rahman, ''Born Gay: The Psychobiology of Human Sex Orientation'', ''op. cit.''</ref>

For humans, the norm is that females possess two X sex chromosomes, while males have one X and one Y. The default developmental pathway for a human fetus being female, the Y chromosome is what induces the changes necessary to shift to the male developmental pathway. This differentiation process is driven by [[androgen]] hormones, mainly [[testosterone]] and [[dihydrotestosterone]] (DHT). The newly formed testicles in the fetus are responsible for the secretion of androgens, which will cooperate in driving the sexual differentiation of the developing fetus, including its brain. This results in sexual differences between males and females.<ref>{{cite journal|last=Siiteri|first=PK|author2=Wilson, JD |title=Testosterone formation and metabolism during male sexual differentiation in the human embryo.|journal=The Journal of Clinical Endocrinology and Metabolism|date=Jan 1974|volume=38|issue=1|pages=113–25|pmid=4809636|doi=10.1210/jcem-38-1-113}}</ref> This fact has led some scientists to test in various ways the result of modifying androgen exposure levels in mammals during fetus and early life.<ref name=Levy>{{cite book|last1=LeVay|first1=Simon|title=Gay, Straight, and the reason why. The science of sexual orientation.|date=2011|publisher=Oxford University Press|isbn=978-0-19-993158-3|pages=45–71, 129–56}}</ref>

==== Birth order ====

{{Main|Fraternal birth order and sexual orientation}}

A significant volume of research has demonstrated that the probability of a male growing up to be gay increases with each older brother he has from the same mother. Known as the ''fraternal birth order'' (FBO) effect, scientists attribute this to a [[Prenatal development|prenatal]] biological mechanism – specifically a maternal immune response to male fetuses – since the effect is only present in men with older biological brothers, and not present among men with older step-brothers and adoptive brothers. This process, known as the ''maternal immunization hypothesis'' (MIH), would begin when cells from a male fetus enter the mother's circulation during pregnancy. These cells carry Y-proteins, which are thought to play a role in brain masculinisation (sex-differentiation) during fetal development. The mother's immune system builds antibodies to these Y-proteins. These antibodies are later released on future male fetuses and interfere with the masculinization role of Y-proteins, leaving regions of the brain responsible for sexual orientation in the 'default' female-typical arrangement, causing the exposed son to be more attracted to men over women. Biochemical evidence for this hypothesis was identified in 2017, finding that mothers with a gay son, especially those with older brothers, had significantly higher levels of anti-bodies to the NLGN4Y Y-protein than mothers with heterosexual sons.<ref name=":22">{{Cite journal|last=Balthazart|first=Jacques|date=2018-01-09|title=Fraternal birth order effect on sexual orientation explained|journal=Proceedings of the National Academy of Sciences of the United States of America|volume=115|issue=2|pages=234–236|doi=10.1073/pnas.1719534115|issn=0027-8424|pmc=5777082|pmid=29259109|bibcode=2018PNAS..115..234B |doi-access=free}}</ref><ref name=":02">{{Cite journal|last1=Bogaert|first1=Anthony F.|author-link1=Anthony Bogaert|last2=Skorska|first2=Malvina N.|last3=Wang|first3=Chao|last4=Gabrie|first4=José|last5=MacNeil|first5=Adam J.|last6=Hoffarth|first6=Mark R.|last7=VanderLaan|first7=Doug P.|last8=Zucker|first8=Kenneth J.|last9=Blanchard|first9=Ray|date=2018-01-09|title=Male homosexuality and maternal immune responsivity to the Y-linked protein NLGN4Y|journal=Proceedings of the National Academy of Sciences of the United States of America|volume=115|issue=2|pages=302–306|doi=10.1073/pnas.1705895114|issn=0027-8424|pmc=5777026|pmid=29229842|bibcode=2018PNAS..115..302B |doi-access=free}}</ref>

The effect becomes stronger with each successive male pregnancy, meaning the odds of the next son being gay increase by 38–48%. This does not mean that all or most sons will be gay after several male pregnancies, but rather, the odds of having a gay son increase from approximately 2% for the first born son, to 4% for the second, 6% for the third and so on.<ref name=":22" /><ref name="Blanchard199722">{{cite journal|author=Blanchard R|year=1997|title=Birth order and sibling sex ratio in homosexual versus heterosexual males and females|journal=Annual Review of Sex Research|volume=8|pages=27–67|doi=10.1080/10532528.1997.10559918 |pmid=10051890}}</ref> Scientists have estimated between 15% and 29% of gay men may owe their sexual orientation to this effect, but the number may be higher, as prior miscarriages and terminations of male pregnancies may have exposed their mothers to Y-linked antigens. The fraternal birth order effect would not likely apply to first born gay sons; instead, scientists say they may owe their orientation to genes, prenatal hormones and other maternal immune responses which also influence brain development.<ref name=":02" /> This effect is nullified if the man is left-handed.<ref>{{Cite journal|last1=Blanchard|first1=R.|last2=Cantor|first2=J.M.|last3=Bogaert|first3=A.F.|author-link3=Anthony Bogaert|last4=Breedlove|first4=S.M.|last5=Ellis|first5=L.|year=2006|title=Interaction of fraternal birth order and handedness in the development of male homosexuality|url=http://msu.edu/~breedsm/pdf/Blanchard2006IntFratHandHBFinal.pdf|journal=Hormones and Behavior|volume=49|issue=3|pages=405–14|doi=10.1016/j.yhbeh.2005.09.002|pmid=16246335|s2cid=16151756|access-date=2007-05-18|archive-date=2020-11-29|archive-url=https://web.archive.org/web/20201129162835/https://msu.edu/~breedsm/pdf/Blanchard2006IntFratHandHBFinal.pdf|url-status=live}}</ref> [[Ray Blanchard]] and [[Anthony Bogaert]] are credited with discovering the effect in the 1990s.<ref>{{Cite journal|last1=Bogaert|first1=Anthony F.|author-link1=Anthony Bogaert|last2=Skorska|first2=Malvina|date=2011-04-01|title=Sexual orientation, fraternal birth order, and the maternal immune hypothesis: A review|url=http://www.sciencedirect.com/science/article/pii/S0091302211000227|journal=Frontiers in Neuroendocrinology|series=Sexual Differentiation of Sexual Behavior and Its Orientation|language=en|volume=32|issue=2|pages=247–254|doi=10.1016/j.yfrne.2011.02.004|pmid=21315103|s2cid=45446175|issn=0091-3022|access-date=2020-07-09|archive-date=2020-07-09|archive-url=https://web.archive.org/web/20200709203424/https://www.sciencedirect.com/science/article/pii/S0091302211000227|url-status=live|url-access=subscription}}</ref> [[J. Michael Bailey]] and [[Jacques Balthazart]] say the FBO effect demonstrates that sexual orientation is heavily influenced by prenatal biological mechanisms rather than unidentified factors in socialization.<ref name=":1">{{Cite journal |last=Bailey |first=J. Michael |date=2018-01-01 |title=The Fraternal Birth Order Effect Is Robust and Important |url=https://link.springer.com/article/10.1007/s10508-017-1115-1 |journal=Archives of Sexual Behavior |language=en |volume=47 |issue=1 |page=18 |doi=10.1007/s10508-017-1115-1 |issn=1573-2800 |pmid=29159754 |s2cid=35597467 |url-access=subscription}}</ref><ref name=":22"/>

=== Social hypotheses ===

{{Main|Environment and sexual orientation}}

In the field of genetics, any factor which is non-genetic is considered an ''environmental influence''. However, environmental influence does not automatically imply that the social environment influences or contributes to the development of sexual orientation. There is a vast non-social environment that is non-genetic yet still biological, such as [[prenatal development]], that likely helps shape sexual orientation.<ref name="Bailey">{{cite journal|vauthors=Bailey JM, Vasey PL, Diamond LM, Breedlove SM, Vilain E, Epprecht M|date=2016|title=Sexual Orientation, Controversy, and Science|journal=[[Psychological Science in the Public Interest]]|volume=17|issue=21|pages=45–101|doi=10.1177/1529100616637616|pmid=27113562|doi-access=free}}</ref>{{rp|76}}

There is no substantive evidence to support the suggestion that early childhood experiences, parenting, sexual abuse, or other adverse life events influence sexual orientation. Hypotheses for the impact of the post-natal social environment on sexual orientation are weak, especially for males.<ref name="Bailey" /> Parental attitudes may affect whether or not children openly identify with their sexual orientation.<ref name="AmPsycholAssn-whatis" /><ref name="pediatrics2004" /><ref name="rcp2007" /><ref>"Different aspects of sexual orientation may be influenced to a greater or lesser degree <nowiki>[</nowiki>p. 303:<nowiki>]</nowiki> by experiential factors such that sexual experimentation with same-gender partners may be more dependent on a conducive family environment than the development of a gay or lesbian identity." Susan E. Golombok & Fiona L. Tasker, ''Do Parents Influence the Sexual Orientation of Their Children?'', in J. Kenneth Davidson Sr. & Nelwyn B. Moore, ''Speaking of Sexuality: Interdisciplinary Readings'' (Los Angeles, Calif.: Roxbury Publishing, 2001) ({{ISBN|1-891487-33-7}}), pp. 302–03 (adapted from same authors, ''Do Parents Influence the Sexual Orientation of Their Children? Findings From a Longitudinal Study of Lesbian Families'', in ''Developmental Psychology'' (American Psychological Association), vol. 32, 1996, 3–11) (author Susan Golombok prof. psychology, City Univ., London, ''id.'', p. xx, & author Fiona Tasker sr. lecturer, Birkbeck Coll., Univ. of London, ''id.'', p. xxiii).</ref><ref>"Whereas there is no evidence from the present investigation to suggest that parents have a determining influence on the sexual orientation of their children, the findings do indicate that by creating a climate of acceptance or rejection of homosexuality within the family, parents may have some impact on their children's sexual experimentation as heterosexual, lesbian, or gay." ''Do Parents Influence the Sexual Orientation of Their Children?'', ''ibid.'', in ''Speaking of Sexuality'', ''id.'', p. 303 (adapted per ''id.'', p. 303).</ref> Though it has since been found to be based on prejudice and misinformation, it was once thought that homosexuality was the result of faulty psychological development, resulting from childhood experiences and troubled relationships, including childhood sexual abuse.<ref name=AmPsycholAssn-whatis /><ref name="AmPsychiAssn-Sexual orientation" /> Such hypotheses "have been associated with highly charged political, moral and theological grounds for wanting to believe that it can".<ref>{{cite journal |last1=Cook |first1=Christopher C. H. |title=The causes of human sexual orientation |journal=Theology & Sexuality |date=2021 |volume=27 |issue=1 |pages=1–19 |doi=10.1080/13558358.2020.1818541|s2cid=225189040 |doi-access=free }}</ref>

=== Influences: professional organizations' statements ===

The [[American Academy of Pediatrics]] in 2004 stated:<ref name="pediatrics2004" />
{{blockquote|The mechanisms for the development of a particular sexual orientation remain unclear, but the current literature and most scholars in the field state that one's sexual orientation is not a choice; that is, individuals do not choose to be homosexual or heterosexual. A variety of theories about the influences on sexual orientation have been proposed. Sexual orientation probably is not determined by any one factor but by a combination of genetic, hormonal, and environmental influences. In recent decades, biologically based theories have been favored by experts. Although there continues to be controversy and uncertainty as to the genesis of the variety of human sexual orientations, there is no scientific evidence that abnormal parenting, sexual abuse, or other adverse life events influence sexual orientation. Current knowledge suggests that sexual orientation is usually established during early childhood.}}

The [[American Psychological Association]], the [[American Psychiatric Association]], and the [[National Association of Social Workers]] in 2006 stated:<ref name="Calif-amici" />
{{blockquote|Currently, there is no scientific consensus about the specific factors that cause an individual to become heterosexual, homosexual, or bisexual – including possible biological, psychological, or social effects of the parents' sexual orientation. However, the available evidence indicates that the vast majority of lesbian and gay adults were raised by heterosexual parents and the vast majority of children raised by lesbian and gay parents eventually grow up to be heterosexual.}}

The [[Royal College of Psychiatrists]] in 2007 stated:<ref name="rcp2007" />
{{blockquote|Despite almost a century of psychoanalytic and psychological speculation, there is no substantive evidence to support the suggestion that the nature of parenting or early childhood experiences play any role in the formation of a person's fundamental heterosexual or homosexual orientation. It would appear that sexual orientation is biological in nature, determined by a complex interplay of genetic factors and the early uterine environment. Sexual orientation is therefore not a choice, though sexual behaviour clearly is.}}

The American Psychiatric Association stated in 2011:<ref name="AmPsychiAssn-Sexual orientation" />
{{blockquote|No one knows what causes heterosexuality, homosexuality, or bisexuality. Homosexuality was once thought to be the result of troubled family dynamics or faulty psychological development. Those assumptions are now understood to have been based on misinformation and prejudice.}}

A legal brief dated September 26, 2007, and presented on behalf of the American Psychological Association, California Psychological Association, American Psychiatric Association, National Association of Social Workers, and National Association of Social Workers, California Chapter, stated:<ref name="Calif-amici" />

{{blockquote|Although much research has examined the possible genetic, hormonal, developmental, social, and cultural influences on sexual orientation, no findings have emerged that permit scientists to conclude that sexual orientation – heterosexuality, homosexuality, or bisexuality – is determined by any particular factor or factors. The evaluation of ''amici'' is that, although some of this research may be promising in facilitating greater understanding of the development of sexual orientation, it does not permit a conclusion based in sound science at the present time as to the cause or causes of sexual orientation, whether homosexual, bisexual, or heterosexual.}}

== Efforts to change sexual orientation ==
{{Main|Sexual orientation change efforts|Conversion therapy}}
[[File:Nottinghamshire Pride 2011 MMB 22.jpg|thumb|Nottinghamshire Pride 2011]]
Sexual orientation change efforts are methods that aim to change a same-sex sexual orientation. They may include behavioral techniques, [[cognitive behavioral therapy]], [[reparative therapy]], psychoanalytic techniques, medical approaches, and religious and spiritual approaches.<ref name="apa2009-2" />

No major mental health professional organization sanctions efforts to change sexual orientation and virtually all of them have adopted policy statements cautioning the profession and the public about treatments that purport to change sexual orientation. These include the American Psychiatric Association, American Psychological Association, American Counseling Association, National Association of Social Workers in the US,<ref name="Calif-amici" /><ref>{{cite web |url = http://www.glad.org/uploads/docs/cases/2009-11-17-doma-aff-herek.pdf |title = Expert affidavit of Gregory M. Herek, Ph.D. |archive-url=https://web.archive.org/web/20100828054600/http://www.glad.org/uploads/docs/cases/2009-11-17-doma-aff-herek.pdf |archive-date=28 August 2010 }}</ref> the Royal College of Psychiatrists,<ref name="royal2009">{{cite web |url=http://www.rcpsych.ac.uk/pdf/RCPsychposstatementsexorientation.pdf |publisher=Royal College of Psychiatrists |title=Royal College of Psychiatrists' Position Statement on Sexual Orientation |archive-url= https://web.archive.org/web/20171002115951/http://www.rcpsych.ac.uk/pdf/RCPsychposstatementsexorientation.pdf |archive-date= Oct 2, 2017 }}</ref> and the Australian Psychological Society.<ref name="aps">[https://web.archive.org/web/20070830140633/http://www.psychology.org.au/publications/tip_sheets/orientation/ Australian Psychological Society: "Sexual orientation and homosexuality"].</ref>

In 2009, the American Psychological Association Task Force on Appropriate Therapeutic Responses to Sexual Orientation conducted a systematic review of the peer-reviewed journal literature on sexual orientation change efforts (SOCE) and concluded:<ref name="apa2009-2" />
<blockquote>Efforts to change sexual orientation are unlikely to be successful and involve some risk of harm, contrary to the claims of SOCE practitioners and advocates. Even though the research and clinical literature demonstrate that same-sex sexual and romantic attractions, feelings, and behaviors are normal and positive variations of human sexuality, regardless of [[sexual orientation identity]], the task force concluded that the population that undergoes SOCE tends to have strongly conservative religious views that lead them to seek to change their sexual orientation. Thus, the appropriate application of affirmative therapeutic interventions for those who seek SOCE involves therapist acceptance, support, and understanding of clients and the facilitation of clients' active coping, social support, and identity exploration and development, without imposing a specific sexual orientation identity outcome.</blockquote>

In 2012, the [[Pan American Health Organization]] (the North and South American branch of the [[World Health Organization]]) released a statement cautioning against services that purport to "cure" people with non-heterosexual sexual orientations, as they lack medical justification, and represent a threat to the health and well-being of affected people. They noted that the global scientific and professional consensus is that homosexuality is a normal and natural variation of [[human sexuality]] and cannot be regarded as a pathological condition. The Pan American Health Organization further called on governments, academic institutions, professional associations and the media to expose these practices and to promote respect for diversity. The World Health Organization affiliate further noted that gay minors have sometimes been forced to attend these "therapies" involuntarily, being deprived of their liberty and sometimes kept in isolation for several months. Additionally, the Pan American Health Organization recommended that such malpractices be denounced and subject to sanctions and penalties under national legislation, as they constitute a violation of the ethical principles of health care and violate [[human rights]] that are protected by international and regional agreements.<ref name="PAHO">{{cite web |date=17 May 2012 |title="Therapies" to change sexual orientation lack medical justification and threaten health |url=https://www.paho.org/en/news/17-5-2012-therapies-change-sexual-orientation-lack-medical-justification-and-threaten-health |publisher=Pan American Health Organization}}</ref>

The [[National Association for Research & Therapy of Homosexuality]] (NARTH), which described itself as a "professional, scientific organization that offers hope to those who struggle with unwanted homosexuality", disagreed with the mainstream mental health community's position on conversion therapy, both on its effectiveness and by describing sexual orientation not as a binary immutable quality, or as a disease, but as a continuum of intensities of sexual attractions and emotional affect.<ref>{{cite journal |author=Spitzer R.L. |year=1981 |title=The diagnostic status of homosexuality in DSM-III: a reformulation of the issues |journal=American Journal of Psychiatry |volume=138 |issue=2 |pages=210–15 |pmid=7457641 |doi=10.1176/ajp.138.2.210}}</ref><ref>[https://web.archive.org/web/20070126194717/http://www.time.com/time/magazine/article/0,9171,904053,00.html "An Instant Cure"], ''Time''; April 1, 1974.</ref><ref>{{cite web |url=http://www.narth.com/docs/normalization.html |title=The A.P.A. Normalization of Homosexuality, and the Research Study of Irving Bieber |archive-url=https://web.archive.org/web/20130729145642/http://www.narth.com/docs/normalization.html |archive-date=2013-07-29}}</ref> The American Psychological Association and the [[Royal College of Psychiatrists]] expressed concerns that the positions espoused by NARTH are not supported by the science and create an environment in which prejudice and discrimination can flourish.<ref name="royal2009" /><ref name="apaexgay">[https://web.archive.org/web/20110514111323/http://www.apa.org/pi/lgbt/resources/policy/ex-gay.pdf Statement of the American Psychological Association].</ref>

==Assessment and measurement==

Varying definitions and strong [[sexual norm|social norms about sexuality]] can make sexual orientation difficult to quantify.

===Early classification schemes===

One of the earliest sexual orientation classification schemes was proposed in the 1860s by [[Karl Heinrich Ulrichs]] in a series of pamphlets he published privately.<ref>{{cite book|last=Ulrichs|first=Karl Heinrich|title=The Riddle of Man-Manly Love|year=1994|publisher=Prometheus Books|isbn=978-0-87975-866-0}}</ref> The classification scheme, which was meant only to describe males, separated them into three basic categories: ''dionings, urnings'' and ''uranodionings''. An ''urning'' can be further categorized by degree of [[effeminacy]]. These categories directly correspond with the categories of sexual orientation used today: ''heterosexual'', ''homosexual'', and ''bisexual''. In the series of pamphlets, Ulrichs outlined a set of questions to determine if a man was an ''urning''. The definitions of each category of Ulrichs' classification scheme are as follows:

:* Dioning – Comparable to the modern term "heterosexual"

:*Urning – Comparable to the modern term "homosexual"
:::Mannling – A manly ''urning''
:::Weibling – An effeminate ''urning''
:::Zwischen – A somewhat manly and somewhat effeminate ''urning''
:::Virilised – An ''urning'' that sexually behaves like a ''dioning''

:*Urano-Dioning – Comparable to the modern term "bisexual"

From at least the late nineteenth century in Europe, there was speculation that the range of human sexual response looked more like a continuum than two or three discrete categories. Berlin sexologist [[Magnus Hirschfeld]] published a scheme in 1896 that measured the strength of an individual's sexual desire on two independent 10-point scales, A (homosexual) and B (heterosexual).<ref>[[Magnus Hirschfeld|Hirschfeld, Magnus]], 1896. ''Sappho und Socrates, Wie erklärt sich die Liebe der Männer & und Frauen zu Personen des eigenen Geschlechts?'' (Sappho and Socrates, How Can One Explain the Love of Men and Women for Individuals of Their Own Sex?).</ref> A heterosexual individual may be A0, B5; a homosexual individual may be A5, B0; an asexual would be A0, B0; and someone with an intense attraction to both sexes would be A9, B9.

===Kinsey scale===

The [[Kinsey scale]], also called the Heterosexual-Homosexual Rating Scale, was first published in ''[[Kinsey Reports|Sexual Behavior in the Human Male]]'' (1948) by [[Alfred Kinsey]], [[Wardell Pomeroy]], and [[Clyde Martin]] and also featured in ''Sexual Behavior in the Human Female'' (1953).<ref>{{cite book|last=Kinsey|title=Sexual Behavior in the Human Female|year=1953|publisher=Indiana University Press|isbn=978-4-87187-704-6|page=499|display-authors=etal}}</ref> The scale was developed to combat the assumption at the time that people are either heterosexual or homosexual and that these two types represent antitheses in the sexual world.<ref>{{cite book|last=Kinsey|title=Sexual Behavior in the Human Male|year=1948|publisher=Indiana University Press|isbn=978-0-253-33412-1|display-authors=etal}}</ref> Recognizing that a significant portion of the population is not completely heterosexual or homosexual and that such people can experience both heterosexual and homosexual behavior and psychic responses, Kinsey et al., stated:
{{blockquote|text=Males do not represent two discrete populations, heterosexual and homosexual. The world is not to be divided into sheep and goats. Not all things are black nor all things white... The living world is a continuum in each and every one of its aspects. The sooner we learn this concerning human sexual behavior, the sooner we shall reach a sound understanding of the realities of sex. |sign=Kinsey et al. (1948) p. 639.}}

The Kinsey scale provides a classification of sexual orientation based on the relative amounts of heterosexual and homosexual experience or psychic response in one's history at a given time. The classification scheme works such that individuals in the same category show the same balance between the heterosexual and homosexual elements in their histories. The position on the scale is based on the relation of heterosexuality to homosexuality in one's history, rather than the actual amount of overt experience or psychic response. An individual can be assigned a position on the scale in accordance with the following definitions of the points of the scale:<ref>{{cite book|last=Kinsey|title=Sexual Behavior in the Human Male|url=https://archive.org/details/sexualbehaviorin00kins|url-access=registration|year=1948|pages=[https://archive.org/details/sexualbehaviorin00kins/page/639 639–41]|publisher=Philadelphia, W. B. Saunders Co.|display-authors=etal}}</ref>

{| class="wikitable"
|-
! Rating !! Description
|-
| 0 || ''Exclusively heterosexual''. Individuals make no physical contact which results in erotic arousal or orgasm and make no psychic responses to individuals of their own sex.
|-
| 1 || ''Predominantly heterosexual/incidentally homosexual''. Individuals have only incidental homosexual contacts which have involved physical or psychic response or incidental psychic response without physical contact.
|-
| 2 || ''Predominantly heterosexual but more than incidentally homosexual''. Individuals have more than incidental homosexual experience or respond rather definitely to homosexual stimuli.
|-
| 3 || ''Equally heterosexual and homosexual''. Individuals are about equally homosexual and heterosexual in their experiences or psychic reactions.
|-
| 4 || ''Predominantly homosexual but more than incidentally heterosexual.'' Individuals have more overt activity or psychic reactions in the homosexual while still maintaining a fair amount of heterosexual activity or responding rather definitively to heterosexual contact.
|-
| 5 || ''Predominantly homosexual/only incidentally heterosexual.'' Individuals are almost entirely homosexual in their activities or reactions.
|-
| 6 || ''Exclusively homosexual.'' Individuals who are exclusively homosexual, both in regard to their overt experience and in regard to their psychic reactions.
|}

The Kinsey scale has been praised for dismissing the dichotomous classification of sexual orientation and allowing for a new perspective on human sexuality. Despite seven categories being able to provide a more accurate description of sexual orientation than a dichotomous scale, it is still difficult to determine which category individuals should be assigned to. In a major study comparing sexual response in homosexual males and females, [[Masters and Johnson]] discuss the difficulty of assigning the Kinsey ratings to participants.<ref>{{cite book|last=Masters and Johnson|title=Homosexuality in Perspective|year=1979|publisher=Little, Brown |isbn=978-0-316-54984-4|url=https://archive.org/details/homosexualityinp00mast}}</ref> Particularly, they found it difficult to determine the relative amount heterosexual and homosexual experience and response in a person's history when using the scale. They report finding it difficult to assign ratings 2–4 for individuals with a large number of heterosexual and homosexual experiences. When there are a substantial number of heterosexual and homosexual experiences in one's history, it becomes difficult for that individual to be fully objective in assessing the relative amount of each.

Weinrich et al. (1993) and Weinberg et al. (1994) criticized the scale for lumping individuals who are different based on different dimensions of sexuality into the same categories.<ref name="Weinrich 1993 157–168">{{cite journal|last=Weinrich|first=J.|title=A factor analysis of the Klein Sexual Orientation Grid in two disparate samples|journal=Archives of Sexual Behavior|year=1993|volume=22|issue=2|pages=157–68|doi=10.1007/bf01542364|pmid=8476335|s2cid=34708645|display-authors=etal}}</ref><ref>{{cite book|last=Weinberg|title=Dual Attraction|year=1994|publisher=Oxford University Press|isbn=978-0-19-508482-5|display-authors=etal|url=https://archive.org/details/dualattractionun00wein}}</ref> When applying the scale, Kinsey considered two dimensions of sexual orientation: overt sexual experience and psychosexual reactions. Valuable information was lost by collapsing the two values into one final score. A person who has only predominantly same sex reactions is different from someone with relatively little reaction but much same sex experience. It would have been quite simple for Kinsey to have measured the two dimensions separately and report scores independently to avoid loss of information. Furthermore, there are more than two dimensions of sexuality to be considered. Beyond behavior and reactions, one could also assess attraction, identification, lifestyle, etc. This is addressed by the [[#Klein Sexual Orientation Grid|Klein Sexual Orientation Grid]].

A third concern with the Kinsey scale is that it inappropriately measures heterosexuality and homosexuality on the same scale, making one a tradeoff of the other.<ref name="Sell 1997 43–58">{{cite journal|last=Sell|first=R.L.|title=Defining and measuring sexual orientation: A review|journal=Archives of Sexual Behavior|year=1997|volume=26|issue=6|pages=643–58|pmid=9415799|doi=10.1023/A:1024528427013|s2cid=29774549}}</ref> Research in the 1970s on masculinity and femininity found that concepts of masculinity and femininity are more appropriately measured as independent concepts on a separate scale rather than as a single continuum, with each end representing opposite extremes.<ref>{{cite book|last=Bem|first=S.L.|title=Bem sex-rol inventory professional manual|year=1981|publisher=Consulting Psychologists Press|location=Palo Alto, CA}}</ref> When compared on the same scale, they act as tradeoffs such, whereby to be more feminine one had to be less masculine and vice versa. However, if they are considered as separate dimensions one can be simultaneously very masculine and very feminine. Similarly, considering heterosexuality and homosexuality on separate scales would allow one to be both very heterosexual and very homosexual or not very much of either. When they are measured independently, the degree of heterosexual and homosexual can be independently determined, rather than the balance between heterosexual and homosexual as determined using the Kinsey Scale.<ref>{{cite journal|last=Shively|first=M.G.|author2=DeCecco, J.P. |title=Components of sexual identity|journal=Journal of Homosexuality|year=1977|volume=3|issue=1|pages=41–48|doi=10.1300/j082v03n01_04|pmid=591712}}</ref>

===Klein Sexual Orientation Grid===

{{main|Klein Sexual Orientation Grid}}
In response to the criticism of the Kinsey scale only measuring two dimensions of sexual orientation, [[Fritz Klein (sex researcher)|Fritz Klein]] developed the Klein sexual orientation grid (KSOG), a multidimensional scale for describing sexual orientation. Introduced in Klein's book ''[[The Bisexual Option]]'' (1978), the KSOG uses a 7-point scale to assess seven different dimensions of sexuality at three different points in an individual's life: past (from early adolescence up to one year ago), present (within the last 12 months), and ideal (what the individual would choose if it were completely their choice).

===The Sell Assessment of Sexual Orientation===

The Sell Assessment of Sexual Orientation (SASO) was developed to address the major concerns with the Kinsey Scale and Klein Sexual Orientation Grid and as such, measures sexual orientation on a continuum, considers various dimensions of sexual orientation, and considers homosexuality and heterosexuality separately. Rather than providing a final solution to the question of how to best measure sexual orientation, the SASO is meant to provoke discussion and debate about measurements of sexual orientation.<ref name="Sell 1997 43–58" />

The SASO consists of 12 questions. Six of these questions assess sexual attraction, four assess sexual behavior, and two assess sexual orientation identity. For each question on the scale that measures homosexuality there is a corresponding question that measures heterosexuality giving six matching pairs of questions. Taken all together, the six pairs of questions and responses provide a profile of an individual's sexual orientation. However, results can be further simplified into four summaries that look specifically at responses that correspond to either homosexuality, heterosexuality, bisexuality or asexuality.<ref name="Sell 1996 295–310">{{cite journal|last=Sell|first=R.L.|title=The Sell assessment of sexual orientation: Background and scoring|journal=Journal of Lesbian, Gay, and Bisexual Identity|year=1996|volume=1|issue=4 |pages=295–310|doi=10.1007/BF03372244 |s2cid=151411037 }}</ref>

Of all the questions on the scale, Sell considered those assessing sexual attraction to be the most important as sexual attraction is a better reflection of the concept of sexual orientation which he defined as "extent of sexual attractions toward members of the other, same, both sexes or neither" than either sexual identity or sexual behavior. Identity and behavior are measured as supplemental information because they are both closely tied to sexual attraction and sexual orientation. Major criticisms of the SASO have not been established, but a concern is that the reliability and validity remains largely unexamined.<ref name="Sell 1996 295–310" />

===Difficulties with assessment===

Research focusing on sexual orientation uses scales of assessment to identify who belongs in which sexual population group. It is assumed that these scales will be able to reliably identify and categorize people by their sexual orientation. However, it is difficult to determine an individual's sexual orientation through scales of assessment, due to ambiguity regarding the definition of sexual orientation. Generally, there are three components of sexual orientation used in assessment. Their definitions and examples of how they may be assessed are as follows:

{| class="wikitable"
|-
! Component !! Definition !! Questions
|-
| Sexual attraction || Attraction toward one sex or the desire to have sexual relations or to be in a primary loving, sexual relationship with one or both sexes || "Have you ever had a romantic attraction to a male? Have you ever had a romantic attraction to a female?"<ref>{{cite journal|last=Udry|first=J.|author2=Chantala, K. |title=Risk factors differ according to same sex and opposite-sex interest|journal=Journal of Biological Sciences|year=2005|volume=37|issue=4|pages=481–97|doi=10.1017/s0021932004006765|pmid=16086450|s2cid=33902115}}</ref>
|-
| Sexual behavior || "Any mutually voluntary activity with another person that involves genital contact and sexual excitement or arousal, that is, feeling really turned on, even if intercourse or orgasm did not occur"<ref>{{cite book|last=Laumann|title=The Social Organization of Sexuality|year=1994|publisher=University of Chicago Press|isbn=978-0-226-46957-7|page=67|display-authors=etal}}</ref>   || "Have you ever had a relationship with someone of your own sex which resulted in sexual orgasm?"<ref name="Eskin2005">{{cite journal|last=Eskin|first=M.|title=Same-sex sexual orientation, childhood sexual abuse, and suicidal behaviour in university students in Turkey|journal=Archives of Sexual Behavior|year=2005|volume=34|pages=185–95|doi=10.1007/s10508-005-1796-8|issue=2|display-authors=etal|pmid=15803252|s2cid=2103633}}</ref>
|-
| Sexual identity || Personally selected, socially and historically bound labels attached to the perceptions and meaning individuals have about their sexual identity. || "Pick from these six options: gay or lesbian; bisexual, but mostly gay or lesbian; bisexual equally gay/lesbian and heterosexual; bisexual but mostly heterosexual; heterosexual; and uncertain, don't know for sure."<ref>{{cite journal|last1=D'Augelli|title=Suicidality patterns and sexual orientation-related factors among lesbian, gay, and bisexual youths|journal=Suicide and Life-Threatening Behavior|year=2001|volume=31|pages=250–64|doi=10.1521/suli.31.3.250.24246|pmid=11577911|last2=Hershberger|first2=SL|last3=Pilkington|first3=NW|issue=3|s2cid=12852593|display-authors=etal}}</ref>
|}

Though sexual attraction, behavior, and identity are all components of sexual orientation, if a person defined by one of these dimensions were congruent with those defined by another dimension it would not matter which was used in assessing orientation, but this is not the case. There is "little coherent relationship between the amount and mix of homosexual and heterosexual behavior in a person's biography and that person's choice to label himself or herself as bisexual, homosexual, or heterosexual".<ref>{{cite book|last=Rust|first=Paula|title=Bisexuality in the United States: A Social Science Reader|year=2000|publisher=Columbia University Press|isbn=978-0-231-10226-1|page=167}}</ref> Individuals typically experience diverse attractions and behaviors that may reflect curiosity, experimentation, social pressure and is not necessarily indicative of an underlying sexual orientation. For example, a woman may have fantasies or thoughts about sex with other women but never act on these thoughts and only have sex with opposite gender partners. If sexual orientation was being assessed based on one's sexual attraction then this individual would be considered homosexual, but her behavior indicates heterosexuality.

As there is no research indicating which of the three components is essential in defining sexual orientation, all three are used independently and provide different conclusions regarding sexual orientation. Savin Williams (2006) discusses this issue and notes that by basing findings regarding sexual orientation on a single component, researchers may not actually capture the intended population. For example, if homosexual is defined by same sex behavior, gay virgins are omitted, heterosexuals engaging in same sex behavior for other reasons than preferred sexual arousal are miscounted, and those with same sex attraction who only have opposite-sex relations are excluded.<ref name="Savin-Williams 2006 40–44">{{cite journal|last=Savin-Williams|first=R.|title=Who's Gay? Does it Matter?|journal=Current Directions in Psychological Science|year=2006|volume=15|pages=40–44|doi=10.1111/j.0963-7214.2006.00403.x|s2cid=40586896}}</ref> Because of the limited populations that each component captures, consumers of research should be cautious in generalizing these findings.

One of the uses for scales that assess sexual orientation is determining what the prevalence of different sexual orientations are within a population. Depending on subject's age, culture and sex, the prevalence rates of homosexuality vary depending on which component of sexual orientation is being assessed: sexual attraction, sexual behavior, or sexual identity. Assessing sexual attraction will yield the greatest prevalence of homosexuality in a population whereby the proportion of individuals indicating they are same sex attracted is two to three times greater than the proportion reporting same sex behavior or identify as gay, lesbian, or bisexual. Furthermore, reports of same sex behavior usually exceed those of gay, lesbian, or bisexual identification.<ref>{{cite book|last=Laumann|title=The Social Organization of Sexuality|year=1994|publisher=University of Chicago Press|isbn=978-0-226-46957-7|page=301|display-authors=etal}}</ref> The following chart demonstrates how widely the prevalence of homosexuality can vary depending on what age, location and component of sexual orientation is being assessed:

{| class="wikitable" style="text-align: center;"
|+ Prevalence of homosexuality
|-
!  !! colspan="2" |  Attraction   !! colspan="2" | Behaviour   !! colspan="2" | Identity
|-
| Country: Age group || Female
|Male|| Female
|Male|| Female
|Male
|-
|
:US: Youth<ref>{{cite journal|last=Mosher|first=W |author2=Chandra, A. |author3=Jones, J.|title=Sexual behaviour and selected health measures: Men and women 15–44 years of age, United States, 2002|journal=Advance Data from Vital and Health Statistics|volume=362}}</ref>
 || 6%
|3%|| 11%
|5%|| 8%
|3%
|-
|
:US: Young adults<ref>{{cite journal|last=Savin-Williams|first=R.|author2=Ream, G.L.|title=Suicide attempts among sexual-minority male youth|journal=Journal of Clinical Child and Adolescent Psychology|year=2003|volume=32|pages=509–22|pmid=14710459|issue=4|doi=10.1207/S15374424JCCP3204_3|s2cid=24999339}}</ref>
 || 13%
|5%|| 4%
|3%|| 4%
|3%
|-
|
:US: Adults<ref>{{cite book|last=Laumann|title=The Social Organization of Sexuality|year=1994|publisher=University of Chicago Press|isbn=978-0-226-46957-7|display-authors=etal}}</ref>
 || 8%
|8%|| 4%
|9%|| 1%
|2%
|-
| Australia: Adults<ref>{{cite journal|last=Dunne|first=M.|author2=Bailey, J. |author3=Kirk, K. |author4=Martin, N. |title=The subtlety of sex –atypicality|journal=Archives of Sexual Behavior|year=2000|volume=29|pages=549–65|doi=10.1023/A:1002002420159|issue=6|pmid=11100262|s2cid=17955872}}</ref>  || 17%
|15%|| 8%
|16%|| 4%
|7%
|-
| Turkey: Young adults<ref name="Eskin2005"/>  || 7%
|6%|| 4%
|5%|| 2%
|2%
|-
| Norway: Adolescents<ref>{{cite journal|last1=Wichstrom |first1=L. |last2=Hegna |first2=K.|title=Sexual orientation and suicide attempt: A longitudinal study of the general Norwegian adolescent population|journal=Journal of Abnormal Psychology|year=2003|volume=112|pages=144–51|doi=10.1037/0021-843X.112.1.144|pmid=12653422|issue=1}}</ref>  || 21%
|9%|| 7%
|6%|| 5%
|5%
|}

The variance in prevalence rates is reflected in people's inconsistent responses to the different components of sexual orientation within a study and the instability of their responses over time. Laumann et al. (1994) found that among U.S. adults 20% of those who would be considered homosexual on one component of orientation were homosexual on the other two dimensions and 70% responded in a way that was consistent with homosexuality on only one of the three dimensions.<ref name="Laumann 1994 303">{{cite book|last=Laumann|title=The Social Organization of Sexuality|year=1994|publisher=University of Chicago Press|isbn=978-0-226-46957-7|page=303|display-authors=etal}}</ref> Furthermore, sexuality may be fluid; for example, a person's sexual orientation identity is not necessarily stable or consistent over time but is subject to change throughout life. Diamond (2003) found that over seven years, two-thirds of the women changed their sexual identity at least once, with many reporting that the label was not adequate in capturing the diversity of their sexual or romantic feelings. Furthermore, women who relinquished bisexual and lesbian identification did not relinquish same sex sexuality and acknowledged the possibility for future same sex attractions or behaviour. One woman stated "I'm mainly straight but I'm one of those people who, if the right circumstance came along, would change my viewpoint".<ref>{{cite journal|last=Diamond|first=L.M.|title=Was it a phase? Young women's relinquishment of lesbian/bisexual identities over a 5-year period|journal=Journal of Personality and Social Psychology|year=2003|volume=84|pages=352–64|doi=10.1037/0022-3514.84.2.352|pmid=12585809|issue=2}}</ref> Therefore, individuals classified as homosexual in one study might not be identified the same way in another depending on which components are assessed and when the assessment is made making it difficult to pin point who is homosexual and who is not and what the overall prevalence within a population may be.<ref name="AmPsycholAssn-whatis" />

====Implications====
Depending on which component of sexual orientation is being assessed and referenced, different conclusions can be drawn about the prevalence rate of homosexuality which has real world consequences. Knowing how much of the population is made up of homosexual individuals influences how this population may be seen or treated by the public and government bodies. For example, if homosexual individuals constitute only 1% of the general population they are politically easier to ignore or than if they are known to be a constituency that surpasses most ethnic and minority groups. If the number is relatively minor then it is difficult to argue for community based same sex programs and services, mass media inclusion of gay role models, or Gay/Straight Alliances in schools. For this reason, in the 1970s, [[Bruce Voeller]], the chair of the [[National Gay and Lesbian Task Force]], perpetuated a common myth that the prevalence of homosexuality is 10% for the whole population by averaging a 13% number for men and a 7% number for women. Voeller generalized this finding and used it as part of the modern gay rights movement to convince politicians and the public that "we [gays and lesbians] are everywhere".<ref>{{cite book|last=Laumann|title=The Social Organization of Sexuality|year=1994|publisher=University of Chicago Press|isbn=978-0-226-46957-7|page=289|display-authors=etal}}</ref>

====Proposed solutions====
In the paper "Who's Gay? Does It Matter?", psychologist [[Ritch Savin-Williams]] proposes two different approaches to assessing sexual orientation until well positioned and psychometrically sound and tested definitions are developed that would allow research to reliably identify the prevalence, causes, and consequences of homosexuality.<ref name="Savin-Williams 2006 40–44" />
He first suggests that greater priority should be given to sexual arousal and attraction over behaviour and identity because it is less prone to self- and other-deception, social conditions and variable meanings. To measure attraction and arousal he proposed that biological measures should be developed and used. There are numerous biological/physiological measures that exist that can measure sexual orientation such as [[#Sexual arousal|sexual arousal]], brain scans, eye tracking, body odour preference, and anatomical variations such as [[Digit ratio|digit-length ratio]] and right or left-handedness.
Secondly, Savin-Williams suggests that researchers should forsake the general notion of sexual orientation altogether and assess only those components that are relevant to the research question being investigated. For example:
* To assess STIs or HIV transmission, measure sexual behaviour
* To assess interpersonal attachments, measure sexual/romantic attraction
* To assess political ideology, measure sexual identity

=== Means of assessment ===

Means typically used include surveys, interviews, cross-cultural studies, physical arousal measurements<ref name="Gonsiorek-Weinrich">{{cite web|url=http://psycnet.apa.org/?fa=main.doiLanding&fuseaction=showUIDAbstract&uid=1996-16078-001|title=PsycNET|website=psycnet.apa.org|access-date=2010-03-20|archive-date=2021-05-11|archive-url=https://web.archive.org/web/20210511080204/https://psycnet.apa.org/?fa=main.doiLanding&fuseaction=showUIDAbstract&uid=1996-16078-001|url-status=live}}</ref> sexual behavior, sexual fantasy, or a pattern of erotic arousal.<ref name="BornGay-p21">Wilson, G., & Q. Rahman, ''Born Gay: The Psychobiology of Human Sex Orientation'' (London: Peter Owen Publishers, 2005), p. 21.</ref> The most common is verbal self-reporting<ref name="Gonsiorek-Weinrich" /> or self-labeling,<ref name="BornGay-p21" /> which depend on respondents being accurate about themselves.<ref name="Gonsiorek-Weinrich" />

====Sexual arousal====
Studying human [[sexual arousal]] has proved a fruitful way of understanding how men and women differ as genders and in terms of sexual orientation. A clinical measurement may use [[penile plethysmograph|penile]] or [[vaginal photoplethysmograph]]y, where genital engorgement with blood is measured in response to exposure to different erotic material.<ref name="BornGay-p21" />

Some researchers who study sexual orientation argue that the concept may apply differently for men and women. A study of sexual arousal patterns<ref name="Arousal and orientation">{{cite journal
|first=Meredith L.
|last=Chivers
|author2=Gerulf Rieger
|author3=Elizabeth Latty
|author4=J. Michael Bailey
|title=A Sex Difference in the Specificity of Sexual Arousal
|year=2004
|doi=10.1111/j.0956-7976.2004.00750.x
|pmid=15482445
|journal=Psychological Science
|volume=15
|issue=11
|pages=736–44
|s2cid=5538811
|url=https://www.gaylawnet.com/ezine/gender/sex_difference.pdf
|access-date=2017-12-10
|archive-date=2018-08-18
|archive-url=https://web.archive.org/web/20180818085417/https://www.gaylawnet.com/ezine/gender/sex_difference.pdf
|url-status=live
}}</ref> found that women, when viewing erotic films which show female-female, male-male and male-female sexual activity (oral sex or penetration), have patterns of arousal which do not match their declared sexual orientations as well as men's. That is, heterosexual and lesbian women's sexual arousal to erotic films do not differ significantly by the genders of the participants (male or female) or by the type of sexual activity (heterosexual or homosexual). Men's sexual arousal patterns tend to be more in line with their stated orientations, with heterosexual men showing more penis arousal to female-female sexual activity and less arousal to female-male and male-male [[Sexual stimulation|sexual stimuli]], and homosexual and bisexual men being more aroused by films depicting male-male intercourse and less aroused by other stimuli.

Another study on men and women's patterns of sexual arousal confirmed<ref name="Arousal and orientation #2">{{cite journal
|first=Meredith L.
|last=Chivers
|author2=J. Michael Bailey.
|title=A sex difference in features that elicit genital response
|year=2005
|doi=10.1016/j.biopsycho.2004.12.002
|pmid=16168255
|journal=Biological Psychology
|volume=70
|issue=2
|pages=115–20|s2cid=7637198
}}
</ref> that men and women have different patterns of arousal, independent of their sexual orientations. The study found that women's genitals become aroused to both human and nonhuman stimuli from movies showing humans of both genders having sex (heterosexual and homosexual) and from videos showing non-human [[primates]] (bonobos) having sex. Men did not show any sexual arousal to non-human visual stimuli, their arousal patterns being in line with their specific sexual interest (women for heterosexual men and men for homosexual men).

These studies suggest that men and women are different in terms of sexual arousal patterns and that this is also reflected in how their genitals react to sexual stimuli of both genders or even to non-human stimuli. Sexual orientation has many dimensions (attractions, [[Human sexual activity|behavior]], [[sexual identity|identity]]), of which sexual arousal is the only product of sexual attractions which can be measured at present with some degree of physical precision. Thus, the fact that women are aroused by seeing non-human primates having sex does not mean that women's sexual orientation includes this type of sexual interest. Some researchers argue that women's sexual orientation depends less on their patterns of sexual arousal than men's and that other components of sexual orientation (like emotional attachment) must be taken into account when describing women's sexual orientations. In contrast, men's sexual orientations tend to be primarily focused on the physical component of attractions and, thus, their sexual feelings are more exclusively oriented according to [[sex]].

More recently,{{Vague|date=October 2020}} scientists have started to focus on measuring changes in brain activity related to sexual arousal, by using [[Neuroimaging|brain-scanning techniques]]. A study on how heterosexual and homosexual men's brains react to seeing pictures of naked men and women has found<ref name="Arousal and orientation #3">{{cite journal
|first1=Adam
|last1=Safron
|last2=Bennett
|first2=Barch
|last3=Bailey
|first3=J. Michael
|last4=Gitelman
|first4=Darren R.
|last5=Parrish
|first5=Todd B.
|last6=Reber
|first6=Paul J.
|title=Neural Correlates of Sexual Arousal in Homosexual and Heterosexual Men
|year=2007
|doi=10.1037/0735-7044.121.2.237
|pmid=17469913
|journal=Behavioral Neuroscience
|volume=121
|issue=2
|pages=237–48
|s2cid=16030669
}}</ref> that both hetero- and homosexual men react positively to seeing their preferred sex, using the same brain regions. The only significant group difference between these orientations was found in the [[amygdala]], a brain region known to be involved in regulating [[fear]].<ref>LeDoux JE, ''The Emotional Brain'' (New York: Simon & Schuster, 1996).</ref>

==Culture==
{{See also|LGBT history|Societal attitudes toward homosexuality|LGBT community and multiculturalism}}
[[File:Gay Pride Paris 2009.jpg|thumb|left|Gay Pride, [[Paris]] 2009]]

Research suggests that sexual orientation is independent of cultural and other social influences, but that open identification of one's sexual orientation may be hindered by [[homophobia|homophobic]]/[[heterosexism|heterosexist]] settings. Social systems such as religion, language and ethnic traditions can have a powerful impact on realization of sexual orientation. Influences of culture may complicate the process of [[#Measuring sexual orientation|measuring sexual orientation]]. The majority of empirical and clinical research on LGBT populations are done with largely white, middle-class, well-educated samples; however, there are pockets of research that document various other cultural groups, although these are frequently limited in diversity of gender and sexual orientation of the subjects.<ref name="Garnets, L. 2003">Garnets, L. & Kimmel, D.C. (Eds.). (2003). Psychological perspectives on lesbian, gay and bisexual experiences. New York: Columbia University Press</ref> Integration of sexual orientation with sociocultural identity may be a challenge for LGBT individuals. Individuals may or may not consider their sexual orientation to define their [[sexual identity]], as they may experience various degrees of [[#Fluidity|fluidity of sexuality]],<ref>{{cite journal | last1 = Mock | first1 = S.E. | last2 = Eibach | first2 = R.P. | year = 2011 | title = Stability and change in sexual orientation identity over a 10-year period in adulthood | journal = Archives of Sexual Behavior | volume =  41| issue = 3| pages =  641–48| doi = 10.1007/s10508-011-9761-1 | pmid=21584828| s2cid = 15771368 }}</ref> or may simply identify more strongly with another aspect of their identity such as family role. American culture puts a great emphasis on individual attributes, and views the self as unchangeable and constant. In contrast, East Asian cultures put a great emphasis on a person's social role within social hierarchies, and view the self as fluid and malleable.<ref>{{cite journal |author1=Markus H.R. |author2=Kitayama S. | year = 1991 | title = Culture and the self: Implications for cognition, emotion, and motivation | journal = Psychological Review | volume = 98 | issue = 2| pages = 224–53 | doi=10.1037/0033-295X.98.2.224|citeseerx=10.1.1.320.1159 |s2cid=13606371 }}</ref> These differing cultural perspectives have many implications on cognition of the self, including perception of sexual orientation.

===Language===
Translation is a major obstacle when comparing different cultures. Many English terms lack equivalents in other languages, while concepts and words from other languages fail to be reflected in the English language.<ref>{{cite journal |author1=Minwalla O. |author2=Rosser B.R.S. |author3=Feldman J. |author4=Varga C. |year=2005 |title=Identity experience among progressive gay Muslims in North America: A qualitative study within Al-Fatiha |url=http://nozizwe.co.za/pdf/CultureHealthSexuality.pdf |journal=Culture, Health & Sexuality |volume=7 |issue=2 |pages=113–28 |doi=10.1080/13691050412331321294 |pmid=16864192 |citeseerx=10.1.1.464.9089 |s2cid=30150323 |access-date=2017-10-26 |archive-date=2020-02-04 |archive-url=https://web.archive.org/web/20200204124102/http://nozizwe.co.za/pdf/CultureHealthSexuality.pdf }}</ref><ref>{{cite journal | last1 = Sechrest | first1 = L. | last2 = Fay | first2 = T.L. | last3 = Zaidi | first3 = M.H. | year = 1972 | title = Problems of Translation in Cross-Cultural Research | journal = Journal of Cross-Cultural Research | volume = 3 | issue = 1| pages = 41–56 | doi = 10.1177/002202217200300103 | s2cid = 145766651 }}</ref> Translation and vocabulary obstacles are not limited to the English language.<ref name="Santaemilia, J. 2008 pp. 181–98">Santaemilia, J. (2008). 'War of words' on New (Legal) Sexual Identities: Spain's Recent Gender-Related Legislation and Discursive Conflict. In J. Santaemilia & P. Bou (Eds.). ''Gender and sexual identities in transition: international perspectives'', pp. 181–98. Newcastle: Cambridge Scholars Publishing.</ref> Language can force individuals to identify with a label that may or may not accurately reflect their true sexual orientation. Language can also be used to signal sexual orientation to others.<ref>Leap, W.L. (1996). Word's Out: Gay Men's English. Minneapolis:University of Minnesota Press.</ref> The meaning of words referencing categories of sexual orientation are negotiated in the mass media in relation to social organization.<ref name="Santaemilia, J. 2008 pp. 181–98" /> New words may be brought into use to describe new terms or better describe complex interpretations of sexual orientation. Other words may pick up new layers or meaning. For example, the heterosexual Spanish terms ''marido'' and ''mujer'' for "husband" and "wife", respectively, have recently been replaced in Spain by the gender-neutral terms ''cónyuges'' or ''consortes'' meaning "spouses".<ref name="Santaemilia, J. 2008 pp. 181–98" />

===Perceptions===
[[File:Hate Hurts Wales - Portrayal of Sexual Orientation Hate Crime.webm|thumb|A video by the [[Welsh Government|Welsh government]] portraying [[Hate crime|hate crimes]] based upon sexual orientation ]]

One person may presume knowledge of another person's sexual orientation based upon perceived characteristics, such as appearance, clothing, voice (cf. [[Gay male speech]]), and accompaniment by and behavior with other people. The attempt to detect sexual orientation in social situations is sometimes colloquially known as [[gaydar]]; some studies have found that guesses based on face photos perform better than chance.<ref>{{cite journal |pmid=22128555 |year=2011 |last1=Rule |first1=NO |title=The influence of target and perceiver race in the categorisation of male sexual orientation |volume=40 |issue=7 |pages=830–39 |journal=Perception |doi=10.1068/p7001|hdl=1807/33198 |s2cid=23790518 |hdl-access=free }}</ref><ref>{{cite journal |pmid=21483863 |year=2011 |last1=Johnson |first1=KL |last2=Ghavami |first2=N |title=At the crossroads of conspicuous and concealable: What race categories communicate about sexual orientation |volume=6 |issue=3 |article-number=e18025 |doi=10.1371/journal.pone.0018025 |pmc=3069043 |journal=PLOS ONE |editor1-last=Gilbert |editor1-first=Sam|bibcode=2011PLoSO...618025J |doi-access=free }}</ref><ref>{{cite journal |pmid=21807952 |year=2011 |last1=Rule |first1=NO |last2=Ishii |first2=K |last3=Ambady |first3=N |last4=Rosen |first4=KS |last5=Hallett |first5=KC |title=Found in translation: Cross-cultural consensus in the accurate categorization of male sexual orientation |volume=37 |issue=11 |pages=1499–507 |doi=10.1177/0146167211415630 |journal=Personality and Social Psychology Bulletin |hdl=1807/33193 |s2cid=3847105 |url=https://tspace.library.utoronto.ca/bitstream/1807/33193/1/Rule_etal%282011-PSPB%29.pdf |access-date=2018-04-20 |archive-date=2021-02-28 |archive-url=https://web.archive.org/web/20210228034357/https://tspace.library.utoronto.ca/bitstream/1807/33193/1/Rule_etal(2011-PSPB).pdf |url-status=live }}</ref> 2015 research suggests that "gaydar" is an alternate label for using [[LGBT stereotypes]] to infer orientation, and that face-shape is not an accurate indication of orientation.<ref name="Cox et al. (2015)">{{cite journal |last1= Cox |first1= William T.L. |last2= Devine |first2= Patricia G. |last3= Bischmann |first3= Alyssa A. |last4= Hyde |first4= Janet S. |year= 2015 |title= Inferences About Sexual Orientation: The Roles of Stereotypes, Faces, and The Gaydar Myth |journal= [[The Journal of Sex Research]] |volume= 52 |issue= 8 |pages= 1–15 |doi= 10.1080/00224499.2015.1015714|pmc= 4731319 |pmid=26219212}}</ref>

Perceived sexual orientation may affect how a person is treated. For instance, in the United States, the [[Federal Bureau of Investigation|FBI]] reported that 15.6% of [[hate crime]]s reported to police in 2004 were "because of a sexual-orientation bias".<ref name="FBI crime">{{Cite news|title=Crime in the United States 2004: Hate Crime |url=https://www.fbi.gov/ucr/cius_04/offenses_reported/hate_crime/index.html |periodical=[[FBI]] |access-date=2007-05-04 |archive-url=https://web.archive.org/web/20070411090510/http://www.fbi.gov/ucr/cius_04/offenses_reported/hate_crime/index.html <!-- Bot retrieved archive --> |archive-date=April 11, 2007 }}</ref> Under the [[United Kingdom|UK]] [[Employment Equality (Sexual Orientation) Regulations 2003]], as explained by Advisory, Conciliation and Arbitration Service,<ref>[http://www.acas.org.uk/index.aspx?articleid=1342 ACAS (About Us)] {{Webarchive|url=https://web.archive.org/web/20191206190343/http://www.acas.org.uk/index.aspx?articleid=1342 |date=2019-12-06 }}, as accessed April 19, 2010.</ref> "workers or job applicants must not be treated less favourably because of their sexual orientation, their perceived sexual orientation or because they associate with someone of a particular sexual orientation".<ref>{{cite web |url = http://www.acas.org.uk/CHttpHandler.ashx?id=105&p=0 |title = Sexual orientation and the workplace: Putting the Employment Equality (Sexual Orientation) Regulations 2003 into practice |archive-url=https://web.archive.org/web/20081219232635/http://www.acas.org.uk/CHttpHandler.ashx?id=105&p=0 |archive-date=19 December 2008 }}</ref>

In Euro-American cultures, norms, values, traditions and laws facilitate heterosexuality,<ref>Rust, P.C. (2003).  Finding a Sexual Identity and Community: Therapeutic Implications and Cultural Assumptions in Scientific Models of Coming Out. In L. Garnets & D.C. Kimmel (Eds.).  Psychological perspectives on lesbian, gay and bisexual experiences (pp. 227–69). New York: Columbia University Press</ref> including constructs of marriage and family.<ref name="Garnets, L. 2003" /> Efforts are being made to change prejudiced attitudes, and legislation is being passed to promote equality.<ref name="Santaemilia, J. 2008 pp. 181–98" />
 
Some other cultures do not recognize a homosexual/heterosexual/bisexual distinction. It is common to distinguish a person's sexuality according to their sexual role (active/passive; insertive/penetrated). In this distinction, the passive role is typically associated with femininity or inferiority, while the active role is typically associated with masculinity or superiority.<ref name="Santaemilia, J. 2008 pp. 181–98" /><ref>{{cite journal |author1=Carballo-Diéguez A. |author2=Dolezal C. |author3=Nieves L. |author4=Díaz F. |author5=Decena C. |author6=Balan I. | year = 2004 | title = Looking for a tall, dark, macho man… sexual-role behaviour variations in Latino gay and bisexual men | journal = Culture, Health & Sexuality | volume = 6 | issue = 2| pages = 159–71 | doi = 10.1080/13691050310001619662 |s2cid=144131628 }}</ref><ref name="Cardoso, F.L. 2005">{{cite journal | author = Cardoso F.L. | year = 2005 | title = Cultural Universals and Differences in Male Homosexuality: The Case of a Brazilian Fishing Village | journal = Archives of Sexual Behavior | volume = 34 | issue = 1| pages = 103–09 | doi =  10.1007/s10508-005-1004-x | pmid = 15772773| s2cid = 28100810 }}</ref> For example, an investigation of a small Brazilian fishing village revealed three sexual categories for men: men who have sex only with men (consistently in a passive role), men who have sex only with women, and men who have sex with women and men (consistently in an active role). While men who consistently occupied the passive role were recognized as a distinct group by locals, men who have sex with only women, and men who have sex with women and men, were not differentiated.<ref name="Cardoso, F.L. 2005" /> Little is known about same-sex attracted females, or sexual behavior between females in these cultures.

===Racism and ethnically relevant support===
{{see also|African-American culture and sexual orientation}}
In the United States, non-Caucasian LGBT individuals may find themselves in a double minority, where they are neither fully accepted or understood by mainly Caucasian LGBT communities, nor are they accepted by their own ethnic group.<ref>{{cite journal | last1 = Cheng | first1 = P. | year = 2011 | title = Gay Asian Masculinities and Christian Theologies | url = http://www.patrickcheng.net/uploads/7/0/3/7/7037096/gay_asian_masculinities_and_christian_theologies.pdf | journal = Cross Currents | volume = 61 | issue = 4 | pages = 540–48 | doi = 10.1111/j.1939-3881.2011.00202.x | s2cid = 170388404 | access-date = 2019-12-01 | archive-date = Dec 7, 2021 | archive-url = https://web.archive.org/web/20211207211811/http://www.patrickcheng.net/uploads/7/0/3/7/7037096/gay_asian_masculinities_and_christian_theologies.pdf | url-status = live }}</ref><ref name="Masequesmay, G. 2003">{{cite journal | last1 = Masequesmay | first1 = G. | year = 2003 | title = Emergence of queer Vietnamese America | journal = Amerasia Journal | volume = 29 | issue = 1 | pages = 117–34 | doi = 10.17953/amer.29.1.l15512728mj65738 | s2cid = 146235953 |s2cid-access=free }}</ref> Many people experience racism in the dominant LGBT community where racial stereotypes merge with gender stereotypes, such that Asian-American LGBTs are viewed as more passive and feminine, while African-American LGBTs are viewed as more masculine and aggressive.<ref name="Garnets, L. 2003" /> There are a number of culturally specific support networks for LGBT individuals active in the United States. For example, "Ô-Môi" for Vietnamese American queer females.<ref name="Masequesmay, G. 2003" />

===Religion===
{{see also|LGBT matters and religion|Religion and homosexuality}}
Sexuality in the context of religion is often a controversial subject, especially that of sexual orientation. In the past, various sects have viewed homosexuality from a negative point of view and had punishments for same-sex relationships. In modern times, an increasing number of religions and religious denominations accept homosexuality. It is possible to integrate sexual identity and religious identity, depending on the interpretation of religious texts.

Some religious organizations object to the concept of sexual orientation entirely. In the 2014 revision of the code of ethics of the American Association of Christian Counselors, members are forbidden to "describe or reduce human identity and nature to sexual orientation or reference," even while counselors must acknowledge the client's fundamental right to self-determination.<ref name=AACC_coe>{{cite web|title=AACC Y-2014 Code of Ethics |url=http://aacc.net/files/AACC%20Code%20of%20Ethics%20-%20Master%20Document.pdf |publisher=American Association of Christian Counselors|access-date=May 21, 2015|archive-url=https://web.archive.org/web/20150213065814/http://aacc.net/files/AACC%20Code%20of%20Ethics%20-%20Master%20Document.pdf|archive-date=February 13, 2015|df=mdy-all}}</ref>

===Internet and media===
{{see also|LGBT stereotypes}}
The Internet has influenced sexual orientation in two ways: it is a common mode of discourse on the subject of sexual orientation and sexual identity, and therefore shapes popular conceptions;<ref name="Santaemilia, J. 2008 pp. 181–98" /> and it allows anonymous attainment of sexual partners, as well as facilitates communication and connection between greater numbers of people.<ref>{{cite journal |last1=Davis |first1=M. |last2=Hart |first2=G. |last3=Bolding |first3=G. |last4=Sherr |first4=L. |last5=Elford |first5=J. |year=2006 |title=Sex and the Internet: Gay men, risk reduction and serostatus |journal=Culture, Health & Sexuality |volume=8 |issue=2 |pages=161–74 |doi=10.1080/13691050500526126 |pmid=16641064 |s2cid=7585088 }}</ref>

== Demographics ==
{{Main|Demographics of sexual orientation}}

Modern scientific surveys find that, across cultures, most people report a heterosexual orientation.<ref name="Bailey" /><ref name=LeVay/>{{rp|8}}<ref name=Balthazart/>{{rp|9–10}} Bisexuality comes in varying degrees of relative attraction to the same or opposite sex.<ref name=Bailey/><ref name=LeVay/>{{rp|8–9}} Men are more likely to be exclusively homosexual than to be equally attracted to both sexes, while the opposite is true for women.<ref name=Bailey/><ref name=LeVay/>{{rp|8–9}}

Surveys in Western cultures find, on average, that about 93% of men and 87% of women identify as completely heterosexual, 4% of men and 10% of women as mostly heterosexual, 0.5% of men and 1% of women as evenly bisexual, 0.5% of men and 0.5% of women as mostly homosexual, and 2% of men and 0.5% of women as completely homosexual.<ref name=Bailey/> An analysis of 67 studies found that the lifetime prevalence of sex between men (regardless of orientation) was 3-5% for East Asia, 6-12% for South and South East Asia, 6-15% for Eastern Europe, and 6-20% for Latin America.<ref>{{cite journal|last1=Caceres|first1=C.|last2=Konda|first2=K.|last3=Pecheny|first3=M.|last4=Chatterjee|first4=A.|last5=Lyerla|first5=R.|title=Estimating the number of men who have sex with men in low and middle income countries|journal=Sexually Transmitted Infections|date=2006|volume=82|issue=Suppl. III|pages=iii3–iii9|doi=10.1136/sti.2005.019489|pmid=16735290|pmc=2576725}}</ref> The [[International HIV/AIDS Alliance]] estimates a worldwide prevalence of [[men who have sex with men]] between 3 and 16%.<ref name="International HIV/AIDS Alliance 2003">{{cite book |author=International HIV/AIDS Alliance |author-link=Frontline AIDS |url=https://www.who.int/hiv/topics/vct/sw_toolkit/Between_men_full_version.pdf |title=Between Men: HIV/STI Prevention For Men Who Have Sex With Men |year=2003 |oclc=896761012 |access-date=2020-10-05 |archive-url=https://web.archive.org/web/20210615021020/https://www.who.int/hiv/topics/vct/sw_toolkit/Between_men_full_version.pdf |archive-date=2021-06-15 }}</ref>

The relative percentage of the population that reports a homosexual or bisexual orientation can vary with different methodologies and selection criteria. A 1998 report stated that these statistical findings are in the range of 2.8 to 9% for males, and 1 to 5% for females for the United States<ref>James Alm, M.V. Lee Badgett, Leslie A. Whittington, ''Wedding Bell Blues: The Income Tax Consequences of Legalizing [[Same-Sex Marriage]]'', p. 24 (1998) [https://web.archive.org/web/20100604013713/http://www.colorado.edu/Economics/CEA/papers98/wp98-33.pdf PDF link].</ref> – this figure can be as high as 12% for some large cities and as low as 1% for rural areas.

A small percentage of people are not sexually attracted to anyone ([[asexuality]]). A study in 2004 placed the prevalence of asexuality at 1%.<ref name="Bogaert2006">{{cite journal |last1=Bogaert |first1=Anthony F |author-link1=Anthony Bogaert |year=2006 |title=Toward a conceptual understanding of asexuality |url=http://cat.inist.fr/?aModele=afficheN&cpsidt=18172400 |journal=Review of General Psychology |volume=10 |issue=3 |pages=241–50 |doi=10.1037/1089-2680.10.3.241 |s2cid=143968129 |access-date=2011-12-17 |archive-date=2012-01-14 |archive-url=https://web.archive.org/web/20120114191419/http://cat.inist.fr/?aModele=afficheN&cpsidt=18172400 |url-access=subscription }}</ref><ref name="cnn">{{cite news |url=http://www.cnn.com/2004/TECH/science/10/14/asexual.study/index.html |title=Study: One in 100 adults asexual |publisher=CNN |access-date=11 November 2007 | date=15 October 2004| archive-url= https://web.archive.org/web/20071027081628/http://www.cnn.com/2004/TECH/science/10/14/asexual.study/index.html| archive-date= 27 October 2007 <!--DASHBot-->| url-status=live}}</ref>

=== Kinsey data ===

In ''[[Kinsey Reports|Sexual Behavior in the Human Male]]'' (1948) and ''Sexual Behavior in the Human Female'' (1953), by [[Alfred C. Kinsey]] et al., people were asked about their sexual behaviors and then assigned a rating by the researchers on a [[Kinsey scale|scale]] from completely heterosexual to completely homosexual.<ref>{{cite web
	| url = https://kinseyinstitute.org/research/publications/kinsey-scale.php
	| title = The Kinsey Scale: Taking the Kinsey test
	| last = 
	| first = 
	| date = 
	| website = The Kinsey Institute
	| access-date = October 13, 2024
	| quote = An official Kinsey "test" does not exist, which is contrary to popular belief and many tests across the web. The original Kinsey research team assigned a number based on a person's sexual history.}}</ref> Kinsey reported that when the individuals' behavior, as well as their identity, are analyzed, a significant number of people appeared to be at least somewhat bisexual – i.e., they have some attraction to either sex, although usually one sex is preferred. Kinsey's methods have been criticized as flawed, particularly with regard to the randomness of his sample population, which included prison inmates, male prostitutes and those who willingly participated in discussion of previously taboo sexual topics. Nevertheless, [[Paul Gebhard]], subsequent director of the [[Kinsey Institute for Sex Research]], reexamined the data in the [[Kinsey Reports]] and concluded that removing the prison inmates and prostitutes barely affected the results.<ref name="MDOG">{{cite web|url=http://www.kinseyinstitute.org/publications/duberman.html |archive-url=https://web.archive.org/web/20020529022730/http://www.kinseyinstitute.org/publications/duberman.html |archive-date=2002-05-29 |title=The Kinsey Institute |work=kinseyinstitute.org }}</ref> More recent researchers believe that Kinsey overestimated the rate of same-sex attraction because of flaws in his sampling methods.<ref name=Bailey/><ref name=Balthazart/>{{rp|9}}<ref name=Lehmiller>{{cite book |last=Lehmiller |first=Justin |date=2018 |title=The Psychology of Human Sexuality |edition=Second |url=https://books.google.com/books?id=JXJGDwAAQBAJ |publisher=John Wiley & Sons Ltd |isbn=978-1-119-16473-9 |access-date=2020-07-16 |archive-date=2020-12-31 |archive-url=https://web.archive.org/web/20201231045623/https://books.google.com/books?id=JXJGDwAAQBAJ |url-status=live }}</ref>{{rp|147}}

==Social constructionism==
{{See also|Queer theory}}

Because sexual orientation is complex, some academics and researchers, especially in [[queer studies]], have argued that it is a historical and [[Social constructionism|social construction]]. In 1976, philosopher and historian [[Michel Foucault]] argued in ''[[The History of Sexuality]]'' that homosexuality as an identity did not exist in the eighteenth century; that people instead spoke of "sodomy", which referred to sexual acts. Sodomy was a crime that was often ignored, but sometimes punished severely under [[sodomy law]]s. He wrote, {{"'}}Sexuality' is an invention of the modern state, the industrial revolution, and capitalism."<ref>[https://books.google.com/books?id=dMAtGvry_IMC&dq=china+heterosexuality+love+western&pg=PA32 ''Chinese Femininities, Chinese Masculinities: A Reader''] {{Webarchive|url=https://web.archive.org/web/20170312212325/https://books.google.com/books?id=dMAtGvry_IMC&pg=PA32&lpg=PA32&dq=china+heterosexuality+love+western&source=web&ots=PKv2BfyPpd&sig=s43w6PzlNOgefEsjpHViwrxkM6A&hl=en&sa=X&oi=book_result&resnum=1&ct=result |date=2017-03-12 }}, by Susan Brownell & Jeffrey N. Wasserstrom (Univ. of Calif. Press, 2002 ({{ISBN|0-520-22116-8}}, {{ISBN|978-0-520-22116-1}})). Quote: "The problem with sexuality: Some scholars have argued that maleness and femaleness were not closely linked to sexuality in China. Michel Foucault's ''[[The History of Sexuality]]'' (which deals primarily with Western civilization and western Europe) began to influence some China scholars in the 1980s. Foucault's insight was to demonstrate that sexuality has a history; it is not fixed psycho-biological drive that is the same for all humans according to their sex, but rather it is a cultural construct inseparable from gender constructs. After unmooring sexuality from biology, he anchored it in history, arguing that this thing we now call sexuality came into existence in the eighteenth-century West and did not exist previously in this form. "Sexuality" is an invention of the modern state, the industrial revolution, and capitalism. Taking this insight as a starting point, scholars have slowly been compiling the history of sexuality in China. The works by Tani Barlow, discussed above, were also foundational in this trend. Barlow observes that, in the West, heterosexuality is the primary site for the production of gender: a woman truly becomes a woman only in relation to a man's heterosexual desire. By contrast, in China before the 1920s the "jia" (linage unit, family) was the primary site for the production of gender: marriage and sexuality were to serve the lineage by producing the next generation of lineage members; personal love and pleasure were secondary to this goal. Barlow argues that this has two theoretical implications: (1) it is not possible to write a Chinese history of heterosexuality, sexuality as an institution, and sexual identities in the European metaphysical sense, and (2) it is not appropriate to ground discussions of Chinese gender processes in the sexed body so central in "Western" gender processes. Here she echoes Furth's argument that, before the early twentieth century, sex-identity grounded on anatomical difference did not hold a central place in Chinese constructions of gender. And she echoes the point illustrated in detail in Sommer's chapter on male homosexuality in the Qing legal code: a man could engage in homosexual behavior without calling into question his manhood so long as his behavior did not threaten the patriarchal Confucian family structure."</ref> Other scholars argue that there are significant continuities between ancient and modern homosexuality.<ref name="Norton 2016">{{cite book |last=Norton |first=Rictor |date=2016 |title=Myth of the Modern Homosexual |url=https://books.google.com/books?id=DkTqDAAAQBAJ |publisher=Bloomsbury Academic |isbn=978-1-4742-8692-3 |access-date=2020-07-16 |archive-date=2021-05-11 |archive-url=https://web.archive.org/web/20210511080439/https://books.google.com/books?id=DkTqDAAAQBAJ |url-status=live }} The author has made adapted and expanded portions of this book available online as [http://rictornorton.co.uk/extracts.htm ''A Critique of Social Constructionism and Postmodern Queer Theory''] {{Webarchive|url=https://web.archive.org/web/20190330132639/http://rictornorton.co.uk/extracts.htm |date=2019-03-30 }}.</ref><ref name="Boswell 1989 17–36">{{cite book |last=Boswell |first=John |chapter=Revolutions, Universals, and Sexual Categories |editor1-last=Duberman |editor1-first=Martin Bauml |editor2-last=Vicinus |editor2-first=Martha |editor3-last=Chauncey |editor3-first=George Jr. |date=1989 |title=Hidden From History: Reclaiming the Gay and Lesbian Past |publisher=Penguin Books |pages=17–36 |s2cid=34904667 |archive-url=https://web.archive.org/web/20190304002205/http://pdfs.semanticscholar.org/d1f4/b4d6d8a37a3470c63ae83bf0d4a5101b08ce.pdf |archive-date=2019-03-04 |chapter-url=http://pdfs.semanticscholar.org/d1f4/b4d6d8a37a3470c63ae83bf0d4a5101b08ce.pdf}}</ref> The philosopher of science [[Michael Ruse]] has stated that the social constructionist approach, which is influenced by Foucault, is based on a selective reading of the historical record that confuses the existence of homosexual people with the way in which they are labelled or treated.<ref>{{cite book |author=Ruse, Michael |editor=Honderich, Ted |title=The Oxford Companion to Philosophy |publisher=Oxford University Press |location=Oxford |year=2005 |page=399 |isbn=0-19-926479-1 |url=https://books.google.com/books?id=bJFCAwAAQBAJ&pg=PT971 |access-date=2020-10-28 |archive-date=2021-05-11 |archive-url=https://web.archive.org/web/20210511080440/https://books.google.com/books?id=bJFCAwAAQBAJ&pg=PT971 |url-status=live }}</ref>

In much of the modern world, [[sexual identity]] is defined based on the sex of one's partner. In some parts of the world, however, sexuality is often socially defined based on sexual roles, whether one is a penetrator or is penetrated.<ref name="International HIV/AIDS Alliance 2003" /><ref>{{cite journal|title=Prevalence of Same-Sex Sexual Behavior and Associated Characteristics among Low-Income Urban Males in Peru|journal=PLOS ONE|date=2007|volume=2|issue=8|article-number=e778|doi=10.1371/journal.pone.0000778|last1=Clark|first1=Jesse L.|last2=Caceres|first2=Carlos F.|last3=Lescano|first3=Andres G.|last4=Konda|first4=Kelika A.|last5=Leon|first5=Segundo R.|last6=Jones|first6=Franca R.|last7=Kegeles|first7=Susan M.|last8=Klausner|first8=Jeffrey D.|last9=Coates|first9=Thomas J.|pmid=17712426|pmc=1945085|bibcode=2007PLoSO...2..778C|doi-access=free}}</ref> In Western cultures, people speak meaningfully of gay, lesbian, and bisexual identities and communities. In some other cultures, homosexuality and heterosexual labels do not emphasize an entire social identity or indicate community affiliation based on sexual orientation.<ref>Zachary Green & Michael J. Stiers, ''Multiculturalism and Group Therapy in the United States: A Social Constructionist Perspective'' (Springer Netherlands, 2002), pp. 233–46.</ref>

Some historians and researchers{{who|date=May 2019}} argue that the emotional and affectionate activities associated with sexual-orientation terms such as "gay" and "heterosexual" change significantly over time and across cultural boundaries. For example, in many English-speaking nations, it is assumed that same-sex kissing, particularly between men, is a sign of homosexuality, whereas various types of same-sex kissing are common expressions of friendship in other nations. Also, many modern and historic cultures have formal ceremonies expressing long-term commitment between same-sex friends, even though homosexuality itself is taboo within the cultures.<ref>Robert Brain, ''Friends and Lovers'' (Granada Publishing Ltd. 1976), chs. 3, 4.</ref>

== Law, politics and theology ==

Professor Michael King stated, "The conclusion reached by scientists who have investigated the origins and stability of sexual orientation is that it is a human characteristic that is formed early in life, and is resistant to change. [[Scientific evidence]] on the origins of homosexuality is considered relevant to theological and social debate because it undermines suggestions that sexual orientation is a choice."<ref>{{cite web|url=http://www.churchtimes.co.uk/content.asp?id=60752|archive-url=https://web.archive.org/web/20090115102447/http://www.churchtimes.co.uk/content.asp?id=60752|archive-date=15 January 2009|title= How much is known about the origins of homosexuality?|publisher=Church Times|date=15 January 2009}}</ref>

In 1999, law professor David Cruz wrote that "sexual orientation (and the related concept homosexuality) might plausibly refer to a variety of different attributes, singly or in combination. What is not immediately clear is whether one conception is most suited to all social, legal, and constitutional purposes."<ref name=Cruz />

== See also ==
{{Portal|Human sexuality|LGBTQ}}
* [[Ascribed characteristics]]
* [[Fundamental Rights Agency]]
* [[Genetic diagnosis of intersex]]
* [[LGBT rights by country or territory]]
* [[List of anti-discrimination acts]]
* [[Queer heterosexuality]]
* [[Romantic orientation]]
* [[Sexual desire]]
* [[Sexual orientation and gender identity at the United Nations]]
* [[Sexual orientation and military service]]
* [[Sexual orientation hypothesis]]
* [[Sociosexual orientation]]
* [[Terminology of homosexuality]]

== References ==
{{Reflist}}

== Further reading ==
* Brum, Gil, Larry McKane, & Gerry Karp, ''Biology: Exploring Life'' (John Wiley & Sons, Inc., 2nd ed. 1994), p.&nbsp;663. {{isbn|9780471600008}}. (About INAH-3.)
* [[Miguel A. De La Torre|De La Torre, Miguel A.]], ''Out of the Shadows, Into the Light: Christianity and Homosexuality'' (Chalice Press, 2009).
* Dynes, Wayne, ed., ''Encyclopedia of Homosexuality''. New York & London: Garland Publishing, 1990.

{{Human sexuality}}
{{Sexual identities}}
{{LGBTQ|selected=identities}}
{{Sexual ethics}}
{{Authority control}}

{{DEFAULTSORT:Sexual Orientation}}
[[Category:Sexual orientation| ]]
[[Category:Interpersonal relationships]]
[[Category:LGBTQ]]