Editing Gender identity (section)

===Biological factors===
Several prenatal biological factors, including genes and hormones, may affect gender identity.<ref name="ZhongNan"/><ref name="Ghosh">{{cite web|vauthors=Ghosh S|title=Gender Identity|url=http://emedicine.medscape.com/article/917990-overview|access-date=29 October 2012|publisher=MedScape|archive-date=6 March 2021|archive-url=https://web.archive.org/web/20210306211817/https://emedicine.medscape.com/article/917990-overview|url-status=live}}</ref> It has been suggested that gender identity is controlled by prenatal [[Sex hormone|sex steroids]], but this is hard to test because there is no way to study gender identity in animals.<ref>{{Cite book|vauthors=Balthazart J|url=https://books.google.com/books?id=3fjGjlcVINkC&q=the+biology+of+gender+identity|title=The Biology of Homosexuality|date=2012|publisher=Oxford University Press, USA|isbn=978-0-19-983882-0|page=5|language=en|author-link=Jacques Balthazart|access-date=18 September 2021|archive-date=17 February 2022|archive-url=https://web.archive.org/web/20220217115728/https://books.google.com/books?id=3fjGjlcVINkC&q=the+biology+of+gender+identity|url-status=live}}</ref> According to biologist [[Michael J Ryan (biologist)|Michael J. Ryan]], gender identity is exclusive to humans.<ref>{{Cite book|vauthors=Ryan MJ|url=https://books.google.com/books?id=-mUxDwAAQBAJ&q=Only+humans+have+gender+identity&pg=PA9|title=A Taste for the Beautiful: The Evolution of Attraction|date=16 January 2018|publisher=Princeton University Press|isbn=978-1-4008-8915-0|page=9|language=en|access-date=18 September 2021|archive-date=11 March 2022|archive-url=https://web.archive.org/web/20220311164835/https://books.google.com/books?id=-mUxDwAAQBAJ&q=Only+humans+have+gender+identity&pg=PA9|url-status=live}}</ref>

In a position statement, the [[Endocrine Society]] stated:<ref name="endocrine-society-position">{{Cite web |date=December 16, 2020 |title=Transgender Health |url=https://www.endocrine.org/advocacy/position-statements/transgender-health |access-date=2022-10-13 |website=www.endocrine.org |language=en |archive-date=10 October 2022 |archive-url=https://web.archive.org/web/20221010143844/https://www.endocrine.org/advocacy/position-statements/transgender-health |url-status=live }}</ref>

{{quote|The medical consensus in the late 20th century was that transgender and gender incongruent individuals suffered a mental health disorder termed "gender identity disorder." Gender identity was considered malleable and subject to external influences. Today, however, this attitude is no longer considered valid. Considerable scientific evidence has emerged demonstrating a durable biological element underlying gender identity. Individuals may make choices due to other factors in their lives, but there do not seem to be external forces that genuinely cause individuals to change gender identity.}}

====Transgender and transsexuality====
{{anchor|Biological causes of transgender and transsexuality}}
{{See also|Causes of transsexuality}}

Some studies have investigated whether there is a link between biological variables and [[transgender]] or [[transsexual]] identity.<ref>{{cite journal | vauthors = Vilain E | title = Genetics of intersexuality. | journal = Journal of Gay & Lesbian Psychotherapy | date = July 2006 | volume = 10 | issue = 2 | pages = 9–26 | doi = 10.1300/J236v10n02_02 | s2cid = 142998821 }}</ref><ref name="pmid15617542">{{cite journal | vauthors = Fleming A, Vilain E | title = The endless quest for sex determination genes | journal = Clinical Genetics | volume = 67 | issue = 1 | pages = 15–25 | date = January 2005 | pmid = 15617542 | doi = 10.1111/j.1399-0004.2004.00376.x | s2cid = 7595544 }}</ref><ref>{{cite journal | vauthors = Savic I, Arver S | title = Sex dimorphism of the brain in male-to-female transsexuals | journal = Cerebral Cortex | volume = 21 | issue = 11 | pages = 2525–2533 | date = November 2011 | pmid = 21467211 | doi = 10.1093/cercor/bhr032 | doi-access = free }} Concluded that gynephilic trans women had brains like men's, but in a few areas, trans women's brains were different from both men's and women's brains.</ref> Several studies have shown that [[Sexual dimorphism|sexually dimorphic]] brain structures in transsexuals are shifted away from what is associated with their birth sex and towards what is associated with their preferred sex.<ref>{{cite journal | vauthors = Gizewski ER, Krause E, Schlamann M, Happich F, Ladd ME, Forsting M, Senf W | title = Specific cerebral activation due to visual erotic stimuli in male-to-female transsexuals compared with male and female controls: an fMRI study | journal = The Journal of Sexual Medicine | volume = 6 | issue = 2 | pages = 440–448 | date = February 2009 | pmid = 18761592 | doi = 10.1111/j.1743-6109.2008.00981.x }} Found that a sample of androphilic trans women was shifted towards the female direction in brain responses.</ref><ref>{{cite journal | vauthors = Rametti G, Carrillo B, Gómez-Gil E, Junque C, Segovia S, Gomez Á, Guillamon A | title = White matter microstructure in female to male transsexuals before cross-sex hormonal treatment. A diffusion tensor imaging study | journal = Journal of Psychiatric Research | volume = 45 | issue = 2 | pages = 199–204 | date = February 2011 | pmid = 20562024 | doi = 10.1016/j.jpsychires.2010.05.006 }} Found that the white matter pattern in gynephilic trans men was shifted in the direction of biological males even before the female-to-male transsexuals started taking male hormones.</ref> The volume of the central subdivision of the [[stria terminalis#Bed nucleus of the stria terminalis|bed nucleus of a stria terminalis]] or BSTc (a constituent of the [[basal ganglia]] of the brain which is affected by [[Prenatal androgen transfer|prenatal androgens]]) of transsexual women has been suggested to be similar to women's and unlike men's,<ref>{{cite book | vauthors = Carlsson NR |title=Psychology: The Science of Behavior |date=2010 |publisher=Allyn & Bacon |location=Boston |isbn=978-0-205-54786-9 |edition=7th | page =418 }}</ref><ref>{{cite journal | vauthors = Zhou JN, Hofman MA, Gooren LJ, Swaab DF | title = A sex difference in the human brain and its relation to transsexuality | journal = Nature | volume = 378 | issue = 6552 | pages = 68–70 | date = November 1995 | pmid = 7477289 | doi = 10.1038/378068a0 | bibcode = 1995Natur.378...68Z | hdl-access = free | type = Submitted manuscript | s2cid = 4344570 | hdl = 20.500.11755/9da6a0a1-f622-44f3-ac4f-fec297a7c6c2 | url = https://pure.knaw.nl/portal/en/publications/a-sex-difference-in-the-human-brain-and-its-relation-to-transsexuality(9da6a0a1-f622-44f3-ac4f-fec297a7c6c2).html | access-date = 6 September 2018 | archive-date = 29 August 2017 | archive-url = https://web.archive.org/web/20170829164452/https://pure.knaw.nl/portal/en/publications/a-sex-difference-in-the-human-brain-and-its-relation-to-transsexuality(9da6a0a1-f622-44f3-ac4f-fec297a7c6c2).html | url-status = live }}</ref> but the relationship between BSTc volume and gender identity is still unclear.<ref>{{cite journal | vauthors = Rosenthal SM | title = Approach to the patient: transgender youth: endocrine considerations | journal = The Journal of Clinical Endocrinology and Metabolism | volume = 99 | issue = 12 | pages = 4379–4389 | date = December 2014 | pmid = 25140398 | doi = 10.1210/jc.2014-1919 | quote = the sexually dimorphic differentiation of the BSTc in humans is not present until puberty, in contrast to rats, where such differences in the BST occur in the early postnatal period and apparently require perinatal differences in T levels (44, 45). Given that many transgender adolescents experience significant gender dysphoria before puberty (and before sex differences in BSTc volume emerge), the relationship between BSTc volume and gender identity would appear to be unclear. | doi-access = free }}</ref> Similar [[Biology and sexual orientation#Studies of brain structure|brain structure differences]] have been noted between gay and heterosexual men, and between lesbian and heterosexual women.<ref name="LeVay 1991">{{cite journal | vauthors = LeVay S | title = A difference in hypothalamic structure between heterosexual and homosexual men | journal = Science | volume = 253 | issue = 5023 | pages = 1034–1037 | date = August 1991 | pmid = 1887219 | doi = 10.1126/science.1887219 | bibcode = 1991Sci...253.1034L | s2cid = 1674111 }}</ref><ref name="Byne 2001">{{cite journal | vauthors = Byne W, Tobet S, Mattiace LA, Lasco MS, Kemether E, Edgar MA, Morgello S, Buchsbaum MS, Jones LB | display-authors = 6 | title = The interstitial nuclei of the human anterior hypothalamus: an investigation of variation with sex, sexual orientation, and HIV status | journal = Hormones and Behavior | volume = 40 | issue = 2 | pages = 86–92 | date = September 2001 | pmid = 11534967 | doi = 10.1006/hbeh.2001.1680 | s2cid = 3175414 }}</ref> Transsexuality has a genetic component.<ref>{{cite book | last1= Klink | first1= Daniel | title= Gender Dysphoria and Disorders of Sex Development |date=2013 | chapter=Genetic Aspects of Gender Identity Development and Gender Dysphoria | series= Focus on Sexuality Research |pages=25–51 |chapter-url=https://rdcu.be/dkOSo |publisher=Springer| doi= 10.1007/978-1-4614-7441-8_2 | isbn= 978-1-4614-7440-1 }}</ref>

Research suggests that the same hormones that promote the differentiation of sex organs in utero also elicit puberty and influence the development of gender identity. Different amounts of these male or female sex hormones can result in behavior and external genitalia that do not match the norm of their sex assigned at birth, and in acting and looking like their identified gender.<ref name="Oswalt">{{cite web| vauthors = Oswalt A |title=Factors Influencing Gender Identity|url=http://www.sevencounties.org/poc/view_doc.php?type=doc&id=37697&cn=1272|url-status=dead|archive-url=https://web.archive.org/web/20101218130452/https://sevencounties.org/poc/view_doc.php?type=doc&id=37697&cn=1272|archive-date=18 December 2010|access-date=29 October 2012|publisher=Seven Countries Services, Inc.}}</ref>

==== Intersex people ====
{{Main|Intersex}}
Estimates of the number of people who are [[intersex]] range from 0.018% to 1.7%, depending on which conditions are counted as intersex.<ref>{{cite journal |vauthors=Blackless M, Charuvastra A, Derryck A, Fausto-Sterling A, Lauzanne K, Lee E |date=March 2000 |title=How sexually dimorphic are we? Review and synthesis |journal=American Journal of Human Biology |volume=12 |issue=2 |pages=151–166 |doi=10.1002/(SICI)1520-6300(200003/04)12:2<151::AID-AJHB1>3.0.CO;2-F |pmid=11534012 |s2cid=453278}}</ref><ref>{{cite journal |vauthors=Sax L |date=August 2002 |title=How common is intersex? a response to Anne Fausto-Sterling |journal=Journal of Sex Research |volume=39 |issue=3 |pages=174–178 |doi=10.1080/00224490209552139 |pmid=12476264 |s2cid=33795209}}</ref> An intersex person is one possessing any of several variations in [[sex]] characteristics including [[chromosome]]s, [[gonad]]s, [[sex hormones]], or [[genital]]s that, according to the United Nations [[Office of the High Commissioner for Human Rights]], "do not fit typical binary notions of male or female bodies".<ref name="unfe-fact">{{cite web |author=<!--Staff writer(s); no by-line.--> |date=2015 |title=Free & Equal Campaign Fact Sheet: Intersex |url=https://unfe.org/system/unfe-65-Intersex_Factsheet_ENGLISH.pdf |url-status=live |archive-url=https://web.archive.org/web/20160304071043/https://unfe.org/system/unfe-65-Intersex_Factsheet_ENGLISH.pdf |archive-date=4 March 2016 |access-date=28 March 2016 |publisher=United Nations [[Office of the High Commissioner for Human Rights]]}}</ref> An intersex variation may complicate initial [[sex assignment]]<ref name="Mieszczak2009">{{cite journal |vauthors=Mieszczak J, Houk CP, Lee PA |date=August 2009 |title=Assignment of the sex of rearing in the neonate with a disorder of sex development |journal=Current Opinion in Pediatrics |volume=21 |issue=4 |pages=541–547 |doi=10.1097/mop.0b013e32832c6d2c |pmc=4104182 |pmid=19444113}}</ref> and that assignment may not be consistent with the child's future gender identity.<ref name="coe">{{Citation |last1=Council of Europe |title=Human rights and intersex people, Issue Paper |date=April 2015 |url=https://wcd.coe.int/ViewDoc.jsp?Ref=CommDH/IssuePaper(2015)1&Language=lanEnglish&Ver=original |access-date=11 March 2022 |archive-url=https://web.archive.org/web/20160106203349/https://wcd.coe.int/ViewDoc.jsp?Ref=CommDH%2FIssuePaper%282015%291&Language=lanEnglish&Ver=original |archive-date=6 January 2016 |url-status=live |last2=Commissioner for Human Rights |author1-link=Council of Europe}}</ref> Reinforcing sex assignments through surgical and hormonal means may violate the individual's [[Intersex human rights|rights]].<ref name="swissnek">{{Cite book |url=http://www.nek-cne.ch/fileadmin/nek-cne-dateien/Themen/Stellungnahmen/en/NEK_Intersexualitaet_En.pdf |title=On the management of differences of sex development. Ethical issues relating to "intersexuality".Opinion No. 20/2012 |date=November 2012 |publisher=Swiss National Advisory Commission on Biomedical Ethics NEK-CNE |location=Berne |access-date=6 October 2016 |archive-url=https://web.archive.org/web/20150423213245/http://www.nek-cne.ch/fileadmin/nek-cne-dateien/Themen/Stellungnahmen/en/NEK_Intersexualitaet_En.pdf |archive-date=23 April 2015 |url-status=dead}}</ref><ref name="who2015">{{Cite book |last=[[World Health Organization]] |title=Sexual health, human rights and the law |date=2015 |publisher=World Health Organization |isbn=978-9241564984 |location=Geneva}}</ref>

A 2005 study on the gender identity outcomes of female-raised [[46,XY]] persons with [[penile agenesis]], [[cloacal exstrophy]] of the bladder, or penile [[ablation]], found that 78% of the study subjects were living as female, as opposed to 22% who decided to initiate a sex change to male in line with their genetic sex.<ref name=":3">{{cite journal |vauthors=Meyer-Bahlburg HF |date=August 2005 |title=Gender identity outcome in female-raised 46,XY persons with penile agenesis, cloacal exstrophy of the bladder, or penile ablation |journal=Archives of Sexual Behavior |volume=34 |issue=4 |pages=423–438 |doi=10.1007/s10508-005-4342-9 |pmid=16010465 |s2cid=34971769}}</ref> The study concludes: "The findings clearly indicate an increased risk of later patient-initiated gender re-assignment to male after female assignment in infancy or early childhood, but are nevertheless incompatible with the notion of a full determination of core gender identity by prenatal androgens."

A 2012 clinical review paper found that between 8.5% and 20% of people with intersex variations experienced [[gender dysphoria]].<ref name="furtado">{{cite journal |vauthors=Furtado PS, Moraes F, Lago R, Barros LO, Toralles MB, Barroso U |date=November 2012 |title=Gender dysphoria associated with disorders of sex development |journal=Nature Reviews. Urology |volume=9 |issue=11 |pages=620–627 |doi=10.1038/nrurol.2012.182 |pmid=23045263 |s2cid=22294512}}</ref> Sociological research in Australia, a country with a third 'X' sex classification, shows that 19% of people born with atypical sex characteristics selected an "X" or "other" option, while 52% are women, 23% men, and 6% unsure. At birth, 52% of persons in the study were assigned female, and 41% were assigned male.<ref name="oiijones">{{cite web |date=3 February 2016 |title=New publication "Intersex: Stories and Statistics from Australia" |url=https://oii.org.au/30313/intersex-stories-statistics-australia/ |url-status=dead |archive-url=https://web.archive.org/web/20160829033933/https://oii.org.au/30313/intersex-stories-statistics-australia/ |archive-date=29 August 2016 |access-date=18 August 2016 |website=[[Organisation Intersex International Australia]]}}</ref><ref name="jones2016">{{Cite book |url=http://oii.org.au/wp-content/uploads/key/Intersex-Stories-Statistics-Australia.pdf |title=Intersex: Stories and Statistics from Australia |vauthors=Jones T, Hart B, Carpenter M, Ansara G, Leonard W, Lucke J |date=2016 |publisher=Open Book Publishers |isbn=978-1-78374-208-0 |location=Cambridge, UK |access-date=2 February 2016 |archive-url=https://web.archive.org/web/20160914152729/http://oii.org.au/wp-content/uploads/key/Intersex-Stories-Statistics-Australia.pdf |archive-date=14 September 2016 |url-status=dead}}</ref>

A study by Reiner & Gearhart provides some insight into what can happen when genetically male children with cloacal exstrophy are sexually assigned female and raised as girls,<ref name="Rosario">{{cite web |author-link=Vernon Rosario |title=Reiner & Gearhart's NEJM Study on Cloacal Exstrophy – Review by Vernon Rosario, M.D., Ph.D |url=http://www.isna.org/node/564 |url-status=live |archive-url=https://web.archive.org/web/20130219025939/http://www.isna.org/node/564 |archive-date=19 February 2013 |access-date=4 April 2011 |website=[[Intersex Society of North America]] |vauthors=Rosario V}}</ref> according to an 'optimal gender policy' developed by [[John Money]]:<ref name="swissnek" /> in a sample of 14 children, follow-up between the ages of 5 and 12 showed that 8 of them identified as boys, and all of the subjects had at least moderately male-typical attitudes and interests,<ref name="Rosario" /> providing support for the argument that genetic variables affect gender identity and behavior independent of socialization.