Editing Gender identity (section)

==Factors influencing formation==

=== Nature versus nurture ===

Although the formation of gender identity is not completely understood, many factors have been suggested as influencing its development. In particular, the extent to which gender identity is determined by nurture (social environmental factors) versus biological factors (which may include non-social environmental factors) is at the core of the ongoing debate in psychology known as "[[nature versus nurture]]".<ref name="ZhongNan">{{cite journal | vauthors = Zhu YS, Cai LQ | title = Effects of male sex hormones on gender identity, sexual behavior, and cognitive function | journal = Zhong Nan da Xue Xue Bao. Yi Xue Ban = Journal of Central South University. Medical Sciences | volume = 31 | issue = 2 | pages = 149–61 | date = April 2006 | pmid = 16706106 }}</ref><ref name=":2">{{Citation |last=Bakker |first=Julie |title=Sex Differentiation: Organizing Effects of Sex Hormones |date=2014 |work=Gender Dysphoria and Disorders of Sex Development: Progress in Care and Knowledge |series=Focus on Sexuality Research |pages=3–23 |editor-last=Kreukels |editor-first=Baudewijntje P.C. |url=https://rdcu.be/dkOR1 |access-date=2024-10-21 |place=Boston, MA |publisher=Springer US |language=en |doi=10.1007/978-1-4614-7441-8_1 |isbn=978-1-4614-7441-8 |editor2-last=Steensma |editor2-first=Thomas D. |editor3-last=de Vries |editor3-first=Annelou L.C.|url-access=subscription }}</ref> There is increasing evidence that the brain is affected by the organizational role of hormones in utero, circulating sex hormones and the expression of certain genes.<ref name=":2" />

Social factors which may influence gender identity include ideas regarding gender roles conveyed by family, authority figures, mass media, and other influential people in a child's life.<ref name="Henslin">{{cite book| vauthors = Henslin JM |title=Essentials of Sociology|publisher=Taylor & Francis|year=2001|isbn=978-0-536-94185-5|pages=65–67, 240}}</ref>{{Clarification needed|date=October 2024}} The [[social learning theory]] posits that children furthermore develop their gender identity through observing and imitating gender-linked behaviors, and then being rewarded or punished for behaving that way, thus being shaped by the people surrounding them through trying to imitate and follow them.<ref name="myers">{{cite book | vauthors = Myers DG | date = 2008 | title = Psychology | location = New York | publisher = Worth }}</ref><ref name="Cognitive theories of early gender">{{cite journal | vauthors = Martin CL, Ruble DN, Szkrybalo J | title = Cognitive theories of early gender development | journal = Psychological Bulletin | volume = 128 | issue = 6 | pages = 903–933 | date = November 2002 | pmid = 12405137 | doi = 10.1037/0033-2909.128.6.903 | citeseerx = 10.1.1.460.3216 }}</ref> 

Large-scale [[Twin study|twin studies]] suggest that the development of both transgender and cisgender gender identities is due to genetic factors, with a small potential influence of unique environmental factors.<ref>{{cite journal |display-authors=6 |vauthors=Polderman TJ, Kreukels BP, Irwig MS, Beach L, Chan YM, Derks EM, Esteva I, Ehrenfeld J, Heijer MD, Posthuma D, Raynor L, Tishelman A, Davis LK |date=March 2018 |title=The Biological Contributions to Gender Identity and Gender Diversity: Bringing Data to the Table |journal=Behavior Genetics |volume=48 |issue=2 |pages=95–108 |doi=10.1007/s10519-018-9889-z |pmid=29460079 |hdl=1871.1/acbbef10-1339-495d-8cc6-0d3f02742596|url=https://research.vu.nl/en/publications/acbbef10-1339-495d-8cc6-0d3f02742596 }}</ref>

==== Case of David Reimer and contrasting case ====
{{further|Nature versus nurture}}
A well-known example in the nature-versus-nurture debate is the case of [[David Reimer]], born in 1965, otherwise known as "John/Joan". As a baby, Reimer went through a faulty circumcision, losing his male genitalia. Psychologist [[John Money]] advised Reimer's parents to raise him as a girl. John Money was instrumental in the early research of gender identity, though he used the term ''gender role''.<ref>{{cite book|vauthors=Zucker KJ|url=https://www.springer.com/gp/book/9781402043130|title=Ethics and Intersex|date=2006|publisher=Springer Netherlands|isbn=978-1-4020-4313-0|veditors=Sytsma SE|page=167|language=en|access-date=14 January 2020|archive-date=8 March 2021|archive-url=https://web.archive.org/web/20210308133040/https://www.springer.com/gp/book/9781402043130|url-status=live}}</ref> He disagreed with the previous school of thought that gender was determined solely by biology. He argued that infants are born a blank slate and a parent could be able to decide their babies' gender.<ref name=":1">{{cite web|title=NOVA {{!}} Transcripts {{!}} Sex: Unknown {{!}} PBS|url=https://www.pbs.org/wgbh/nova/transcripts/2813gender.html|access-date=7 December 2018|website=www.pbs.org|archive-date=11 October 2011|archive-url=https://web.archive.org/web/20111011043248/http://www.pbs.org/wgbh/nova/transcripts/2813gender.html|url-status=live}}</ref> In Money's opinion, if the parent confidently raised their child as the opposite sex from earlier than age two, the child would believe that they were born that sex and act accordingly.<ref name=":0">{{Cite book| vauthors = Colapinto J |title=[[As Nature Made Him: The Boy Who Was Raised as a Girl]]|date=2006|publisher=HarperCollins|isbn=978-0061120565|edition=1st Harper Perennial|location=New York|oclc=71012749|author-link=John Colapinto|pages=19–20}}</ref> Money believed that nurture could override nature.<ref name=":1" />

Reimer underwent [[sex reassignment surgery]] at seventeen months and grew up as a girl, dressing in girl clothes and surrounded by girl toys. In the early 1970s, Money reported that Reimer's [[Sex assignment|sex reassignment]] to female was a success, influencing the academic consensus toward the nurture hypothesis, and for the following 30 years, it became standard medical practice to reassign [[intersex]] infants and male infants with [[micropenis]]es to female.<ref name=":1" />

After Reimer tried to commit suicide at age 13, he was told that he had been born with male genitalia. Reimer stopped seeing Money, and underwent surgery to remove his breasts and reconstruct his genitals.<ref>{{cite book |title=Abnormal Psychology |vauthors=Nolen-Hoeksema S |date=2014 |publisher=McGraw-Hill |isbn=978-1-308-21150-3 |edition=6 |page=368}}<!--|access-date=5 December 2014--></ref> In 1997, sexologist [[Milton Diamond]] published a follow-up, revealing that Reimer had rejected his female reassignment, and arguing against the blank slate hypothesis and infant sex reassignment in general.<ref>{{Cite journal |last1=Diamond |first1=Milton |last2=Sigmundson |first2=H. Keith |date=1 March 1997 |title=Sex Reassignment at Birth: Long-term Review and Clinical Implications |journal=Archives of Pediatrics & Adolescent Medicine |volume=151 |issue=3 |pages=298–304 |doi=10.1001/archpedi.1997.02170400084015 |pmid=9080940 }}</ref>

Diamond was a longtime opponent of Money's theories. Diamond had contributed to research involving pregnant rats that showed hormones played a major role in the behavior of different sexes.<ref name=":0" />{{Page needed|date=August 2021}} The researchers in the lab would inject the pregnant rat with testosterone, which would then find its way to the baby's bloodstream.<ref name=":1" /> The females that were born had genitalia that looked like male genitalia. The females in the litter also behaved like male rats and would even try to mount other female rats, proving that biology played a major role in animal behavior.<ref name=":0" />{{Page needed|date=August 2021}}

One criticism of the Reimer case is that Reimer lost his penis at the age of eight months and underwent sex reassignment surgery at seventeen months, which possibly meant that Reimer had already been influenced by his socialization as a boy. Bradley et al. (1998) report the contrasting case of a 26-year-old woman with XY chromosomes whose penis was lost and who underwent sex reassignment surgery between two and seven months of age (substantially earlier than Reimer), whose parents were also more committed to raising their child as a girl than Reimer's, and who remained a woman into adulthood. She reported that she had been somewhat tomboyish during childhood, enjoying stereotypically masculine childhood toys and interests, although her childhood friends were girls. While she was [[bisexual]], having had relationships with both men and women, she found women more sexually attractive and they featured more in her fantasies. Her job at the time of the study was a blue-collar occupation that was practiced almost exclusively by men.<ref>{{cite journal | vauthors = Bradley SJ, Oliver GD, Chernick AB, Zucker KJ | title = Experiment of nurture: ablatio penis at 2 months, sex reassignment at 7 months, and a psychosexual follow-up in young adulthood | journal = Pediatrics | volume = 102 | issue = 1 | pages = e9 | date = July 1998 | pmid = 9651461 | doi = 10.1542/peds.102.1.e9 | quote = The present case report is a long-term psychosexual follow-up on a second case of ablatio penis in a 46 XY male. | doi-access = free }}</ref> Griet Vandermassen argues that since these are the only two cases being documented in scientific literature, this makes it difficult to draw any firm conclusions from them about the origins of gender identity, particularly given the two cases reached different conclusions. However, Vandermassen also argued that transgender people support the idea of gender identity as being biologically rooted, as they do not identify with their anatomical sex despite being raised and their behaviour reinforced according to their anatomical sex.<ref>{{cite book | vauthors = Vandermassen G |title=Who's Afraid of Charles Darwin?: Debating Feminism and Evolutionary Theory. |date=2005 |publisher=Rowman & Littlefield Publishers |location=Lanham |isbn=978-1-4616-4707-2 | pages = 112–113 }}</ref>

==== Other cases ====
One study by Reiner et al. looked at fourteen genetic males who had suffered [[cloacal exstrophy]] and were thus raised as girls. Six of them changed their gender identity to male, five remained female and three had ambiguous gender identities (though two of them had declared they were male). All the subjects had moderate to marked interests and attitudes consistent with that of biological males.<ref name="pmid14736925">{{cite journal | vauthors = Reiner WG, Gearhart JP | title = Discordant sexual identity in some genetic males with cloacal exstrophy assigned to female sex at birth | journal = The New England Journal of Medicine | volume = 350 | issue = 4 | pages = 333–41 | date = January 2004 | pmid = 14736925 | pmc = 1421517 | doi = 10.1056/NEJMoa022236 }}</ref> Another study,<ref name=":3" /> using data from a variety of cases from the 1970s to the early 2000s (including Reiner et al.), looked at males raised as females due to a variety of developmental disorders ([[penile agenesis]], cloacal exstrophy or penile ablation). It found that 78% of those males raised as females were living as females.<ref name="pmid25667367">{{cite journal | vauthors = Saraswat A, Weinand JD, Safer JD | title = Evidence supporting the biologic nature of gender identity | journal = Endocrine Practice | volume = 21 | issue = 2 | pages = 199–204 | date = February 2015 | pmid = 25667367 | doi = 10.4158/EP14351.RA }}</ref> A minority of those raised as female later switched to male. However, none of the males raised as male switched their gender identity. Those still living as females still showed marked masculinisation of gender role behaviour and those old enough reported sexual attraction to women. The study's authors caution drawing any strong conclusions from it due to numerous methodological caveats which were a severe problem in studies of this nature. Rebelo et al. argue that the evidence in totality suggests that gender identity is neither determined entirely by childhood rearing nor entirely by biological factors.<ref name="pmid18287184">{{cite journal | vauthors = Rebelo E, Szabo CP, Pitcher G | title = Gender assignment surgery on children with disorders of sex development: a case report and discussion from South Africa | journal = Journal of Child Health Care | volume = 12 | issue = 1 | pages = 49–59 | date = March 2008 | pmid = 18287184 | doi = 10.1177/1367493507085618 | s2cid = 46058150 }}</ref>

===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.

===Social and environmental factors===

In 1955, John Money proposed that gender identity was malleable and determined by whether a child was raised as male or female in early childhood.<ref name="pmid13260820">{{cite journal | vauthors = Money J, Hampson JG, Hampson JL | title = An examination of some basic sexual concepts: the evidence of human hermaphroditism | journal = Bulletin of the Johns Hopkins Hospital | volume = 97 | issue = 4 | pages = 301–19 | date = October 1955 | pmid = 13260820 | url = https://books.google.com/books?id=7-IaAQAAMAAJ&pg=PA301 | access-date = 6 December 2022 | archive-date = 6 December 2022 | archive-url = https://web.archive.org/web/20221206034531/https://books.google.com/books?id=7-IaAQAAMAAJ&pg=PA301 | url-status = live }}</ref><ref name="GDDSD">{{cite book | vauthors = Kreukels BP, Steensma TD, de Vries AL |title=Gender dysphoria and disorders of sex development: progress in care and knowledge |date=2014 |publisher=Springer |location=New York |isbn=978-1-4614-7441-8}}</ref> Money's hypothesis has since been discredited,<ref name="GDDSD"/><ref>{{cite book | vauthors = Fausto-Sterling A |title=Sexing the body: gender politics and the construction of sexuality |date=2000 |publisher=Basic Books |location=New York, NY |isbn=978-0-465-07713-7 |edition=1st}}</ref> but scholars have continued to study the effect of social factors on gender identity formation.<ref name="GDDSD"/> In the 1960s and 1970s, factors such as the absence of a father, a mother's wish for a daughter, or parental reinforcement patterns were suggested as influences; more recent theories suggesting that parental [[psychopathology]] might partly influence gender identity formation have received only minimal empirical evidence,<ref name="GDDSD"/> with a 2004 article noting that "solid evidence for the importance of postnatal social factors is lacking."<ref name="pmid15724806">{{cite journal | vauthors = Swaab DF | title = Sexual differentiation of the human brain: relevance for gender identity, transsexualism and sexual orientation | journal = Gynecological Endocrinology | volume = 19 | issue = 6 | pages = 301–12 | date = December 2004 | pmid = 15724806 | doi = 10.1080/09513590400018231 | s2cid = 1410435 | quote = "...direct effects of testosterone on the developing fetal brain are of major importance for the development of male gender identity and male heterosexual orientation. Solid evidence for the importance of postnatal social factors is lacking." }}</ref> A 2008 study found that the parents of [[Gender dysphoria|gender-dysphoric]] children showed no signs of psychopathological issues aside from mild depression in the mothers.<ref name="pmid18981931">{{cite journal | vauthors = Wallien MS, Cohen-Kettenis PT | title = Psychosexual outcome of gender-dysphoric children | journal = Journal of the American Academy of Child and Adolescent Psychiatry | volume = 47 | issue = 12 | pages = 1413–23 | date = December 2008 | pmid = 18981931 | doi = 10.1097/CHI.0b013e31818956b9 }}</ref> It has also been suggested that the attitudes of the child's parents may affect the child's gender identity, although evidence is minimal.<ref name="pmid6488962">{{cite journal | vauthors = Weinraub M, Clemens LP, Sockloff A, Ethridge T, Gracely E, Myers B | title = The development of sex role stereotypes in the third year: relationships to gender labeling, gender identity, sex-typed toy preference, and family characteristics | journal = Child Development | volume = 55 | issue = 4 | pages = 1493–503 | date = August 1984 | pmid = 6488962 | doi = 10.2307/1130019| jstor = 1130019 | quote = Previous investigators have failed to observe a relationship between parental attitudes and children's early sex role acquisition... }}</ref>

====Parental establishment of gender roles====
Parents who do not support gender nonconformity are more likely to have children with firmer and stricter views on gender identity and gender roles.<ref name="Oswalt"/> Recent literature suggests a trend towards less well-defined gender roles and identities, as studies of the parental association ("coding") of toys as masculine, feminine, or neutral indicate that parents increasingly code kitchens and in some cases dolls as neutral rather than exclusively feminine.<ref name="Kane">{{cite book| vauthors = Spade J |url= https://archive.org/details/kaleidoscopeofge0000unse_c1n2/page/177 |title=The Kaleidoscope of Gender|date=2010|publisher=Sage|isbn=978-1-4129-7906-1|location=London|pages=[https://archive.org/details/kaleidoscopeofge0000unse_c1n2/page/177 177–84]}}</ref> However, Emily Kane found that many parents still showed negative responses to items, activities, or attributes that were considered feminine, such as domestic skills, nurturance, and empathy.<ref name=Kane /> Research has indicated that many parents attempt to define gender for their sons in a manner that distances the sons from femininity,<ref name=Kane /> with Kane stating that "the parental boundary maintenance work evident for sons represents a crucial obstacle limiting boys' options, separating boys from girls, devaluing activities marked as feminine for both boys and girls, and thus bolstering gender inequality and heteronormativity."<ref name=Kane />

Many parents form gendered expectations for their child before it is even born, after determining the child's sex through technology such as [[ultrasound]]. The child thus is born to a gender-specific name, games, and even ambitions.<ref name="Ghosh"/> Once the child's sex is determined, most children are raised to in accordance with it, fitting a male or female gender role defined partly by the parents.

When considering the parents' social class, lower-class families typically hold traditional gender roles, where the father works and the mother, who may only work out of financial necessity, still takes care of the household. However, middle-class "professional" couples typically negotiate the division of labor and hold an egalitarian ideology. These different views on gender can shape the child's understanding of gender as well as the child's development of gender.<ref name="Halpern">{{cite journal | vauthors = Halpern HP, Perry-Jenkins M | title = Parents' Gender Ideology and Gendered Behavior as Predictors of Children's Gender-Role Attitudes: A Longitudinal Exploration | journal = Sex Roles | volume = 74 | issue = 11 | pages = 527–542 | date = May 2016 | pmid = 27445431 | pmc = 4945126 | doi = 10.1007/s11199-015-0539-0 }}</ref>

A study conducted by Hillary Halpern<ref name="Halpern" /> demonstrated that parental gender behaviors, rather than beliefs, are better predictors of a child's attitude on gender. A mother's behavior was especially influential on a child's assumptions of the child's own gender. For example, mothers who practiced more traditional behaviors around their children resulted in the son displaying fewer stereotypes of male roles while the daughter displayed more stereotypes of female roles. No correlation was found between a father's behavior and his children's knowledge of stereotypes of their own gender. Fathers who held the belief of equality between the sexes had children, especially sons, who displayed fewer preconceptions of their opposite gender.