Editing Gender identity (section)

=== 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>