Editing Heterosexuality (section)

== Academic study ==
=== Biological and environmental===
{{Main|Biology and sexual orientation|Environment and sexual orientation}}
No simple and singular determinant for [[sexual orientation]] has been conclusively demonstrated, but scientists believe that a combination of genetic, hormonal, and environmental factors determine sexual orientation.<ref name="pediatrics2004" /><ref name="Lamanna"/><ref name="Stuart"/> They favor biological theories for explaining the causes of sexual orientation,<ref name=Bailey16/><ref name="pediatrics2004"/> as there is considerably more evidence supporting nonsocial, biological causes than social ones, especially for males.<ref name=Bailey16/><ref name=LeVay/><ref name=Balthazart/>

Factors related to the development of a heterosexual orientation include [[gene]]s, [[Prenatal hormones and sexual orientation|prenatal hormones]], and [[Human brain|brain]] structure, and their interaction with the environment.

==== Prenatal hormones ====
{{Main|Prenatal hormones and sexual orientation|Neuroscience and sexual orientation}}
{{multiple image
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 | width1 = 168
 | image1 = 2AM9.png
 | caption1 = Structure of the [[androgen receptor]] (rainbow cartoon) complexed with testosterone (white sticks).<ref name="pmid16641486">{{PDB|2AM9}}; {{cite journal |vauthors=Pereira de Jésus-Tran K, Côté PL, Cantin L, Blanchet J, Labrie F, Breton R | title = Comparison of crystal structures of human androgen receptor ligand-binding domain complexed with various agonists reveals molecular determinants responsible for binding affinity | journal = Protein Sci. | volume = 15 | issue = 5 | pages = 987–99 | date =May 2006 | pmid = 16641486 | pmc = 2242507 | doi = 10.1110/ps.051905906 }}</ref>
 | width2 = 185
 | image2 = Testosterone-from-xtal-3D-balls.png
 | caption2 = [[Testosterone]] contributes to the masculinization of the brain
 | width3 = 200
 | image3 = Oestradiol-3D-balls.png
 | caption3 = [[Estradiol]] also stimulates the [[androgen receptor]]s.
 }}

The neurobiology of the masculinization of the brain is fairly well understood. [[Estradiol]] and [[testosterone]], which is catalyzed by the enzyme [[5α-reductase]] into [[dihydrotestosterone]], act upon [[androgen receptor]]s in the brain to masculinize it. If there are few androgen receptors (people with [[androgen insensitivity syndrome]]) or too much androgen (females with [[congenital adrenal hyperplasia]]), there can be physical and psychological effects.<ref>Vilain, E. (2000). Genetics of Sexual Development. Annual Review of Sex Research, 11:1–25</ref> It has been suggested that both male and female heterosexuality are the results of this process.<ref>Wilson, G. and Rahman, Q., (2005). Born Gay. Chapter 5. London: Peter Owen Publishers</ref> In these studies heterosexuality in females is linked to a lower amount of masculinization than is found in lesbian females, though when dealing with male heterosexuality there are results supporting both higher and lower degrees of masculinization than homosexual males.

==== Animals and reproduction ====
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 | image1 = Bonobo sexual behavior 1.jpg
 | caption1 = Bonobos mating, [[Jacksonville Zoo and Gardens]].
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 | image2 = Hoverflies mating midair.jpg
 | caption2 = [[Hoverfly|Hoverflies]] mating in midair flight.
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{{Main|Animal sexual behaviour|Mating}}
{{See also|Pair bond|Mating call}}

Sexual reproduction in the [[animalia|animal world]] is facilitated through opposite-sex sexual activity, although there are also animals that [[Asexual reproduction|reproduce asexually]], including [[protozoa]] and lower [[invertebrates]].<ref>''The Columbia Encyclopedia'' (Colum. Univ. Press, 5th ed. <nowiki>[</nowiki>casebound?<nowiki>]</nowiki> 1993 ({{ISBN|0-395-62438-X}})), entry ''Reproduction''.</ref>

Reproductive sex does not require a heterosexual orientation, since sexual orientation typically refers to a long-term enduring pattern of sexual and emotional attraction leading often to long-term social bonding, while reproduction requires as little as a single act of [[Copulation (zoology)|copulation]] to [[Fertilisation|fertilize]] the [[ovum]] by [[sperm]].<ref>{{cite web|url=http://www.goaskalice.columbia.edu/0116.html |title=Go Ask Alice!: Pregnant without intercourse? |access-date=January 24, 2016 |url-status=dead |archive-url=https://web.archive.org/web/20111222043503/http://www.goaskalice.columbia.edu/0116.html |archive-date=December 22, 2011 }}</ref><ref>{{cite web|url=http://www.americanpregnancy.org/preventingpregnancy/pregnancyfaqmyths.html |title=Can Pregnancy Occur &#124; Pregnancy Myths on How Pregnancy Occurs |website=Americanpregnancy.org |date= 2012-04-24|access-date=2016-07-07}}</ref><ref>Lawyers Guide to Forensic Medicine SBN 978-1-85941-159-9 By Bernard Knight - Page 188 "Pregnancy is well known to occur from such external ejaculation ..."</ref>

===Sexual fluidity===
{{Main|Sexual identity|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="Rosario et al.">{{cite journal | last1 = Rosario | first1 = M. | last2 = Schrimshaw | first2 = E. | last3 = Hunter | first3 = J. |last4 = Braun | first4 = L. | year = 2006 | title = Sexual identity development among lesbian, gay, and bisexual youths: Consistency and change over time | journal = Journal of Sex Research | volume = 43 | issue = 1| pages = 46–58 | doi=10.1080/00224490609552298| pmc = 3215279 | pmid=16817067}}</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 unlikely to change 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|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|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.|pmid=27113562|doi-access=free}}
*{{cite book|first1=Dennis |last1=Coon|first2=John O. |last2=Mitterer|title=Introduction to Psychology: Gateways to Mind and Behavior with Concept Maps and Reviews|publisher=[[Cengage Learning]]|isbn=978-1111833633|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|first1=Eric |last1=Anderson|first2=Mark |last2=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.}}</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}}</ref>

A 2012 study found that 2% of a sample of 2,560 adult participants reported a change of sexual orientation identity after a 10-year period. For men, a change occurred in 0.78% of those who had identified as heterosexual, 9.52% of homosexuals, and 47% of bisexuals. For women, a change occurred in 1.36% of heterosexuals, 63.6% of lesbians, and 64.7% of bisexuals.<ref>{{cite journal | url = http://midus.wisc.edu/findings/pdfs/1153.pdf | author1 = Mock, S. E.|author2= Eibach, R. P. | year = 2012 | 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 = 641–648 | doi = 10.1007/s10508-011-9761-1 | pmid=21584828| s2cid = 15771368}}</ref>

A 2-year study by [[Lisa M. Diamond]] on a sample of 80 non-heterosexual female adolescents (age 16–23) reported that half of the participants had changed sexual-minority identities more than once, one third of them during the 2-year follow-up. Diamond concluded that "although sexual attractions appear fairly stable, sexual identities and behaviors are more fluid."<ref>{{cite journal | author = Diamond, L. M. | year = 2000 | title = Sexual identity, attractions, and behavior among young sexual-minority women over a 2-year period | journal = Developmental Psychology | volume = 36 | issue = 2 | pages = 241–250 | doi = 10.1037/0012-1649.36.2.241 | url = http://www.psych.utah.edu/people/people/diamond/Publications/Sexual%20identity,%20attractions,%20and%20behavior.pdf | pmid = 10749081 | access-date = 2015-04-20 | archive-url = https://web.archive.org/web/20100610021104/http://www.psych.utah.edu/people/people/diamond/Publications/Sexual%20identity%2C%20attractions%2C%20and%20behavior.pdf | archive-date = 2010-06-10 | url-status = dead }}</ref>

[[Heteroflexibility]] is a form of sexual orientation or [[situational sexual behavior]] characterized by minimal homosexual activity in an otherwise primarily heterosexual orientation that is considered to distinguish it from bisexuality. It has been characterized as "mostly straight".<ref>{{cite journal |doi=10.1037/0012-1649.44.1.15 |last1=Thompson |first1=E.M. |last2=Morgan |first2=E.M. |year=2008 |title="Mostly straight" young women: Variations in sexual behavior and identity development |journal=Developmental Psychology |volume=44 |issue=1 |pages=15–21 |pmid=18194001}}</ref>

===Sexual orientation change efforts===
{{Main|Sexual orientation change efforts}}
Sexual orientation change efforts are methods that aim to change sexual orientation, used to try to convert homosexual and bisexual people to heterosexuality. Scientists and mental health professionals generally do not believe that sexual orientation is a choice.<ref name="pediatrics2004" /><ref name="Kersey-Matusiak"/> There are no studies of adequate scientific rigor that conclude that sexual orientation change efforts are effective.<ref name="apa2009">American Psychological Association: [http://www.apa.org/about/governance/council/policy/sexual-orientation.aspx Resolution on Appropriate Affirmative Responses to Sexual Orientation Distress and Change Efforts]</ref>