Research purporting to demonstrate that trans-identifying individualsâ brains resemble those of the opposite sex often ignores a major confo
By: Colin Wright, Samuel Stagg, Christina Buttons
Published: Mar 14, 2025
Earlier this week, City Journal published the tragic story of Yarden Silveira, a young detransitionerâsomeone who pursues hormonal and/or surgical âsex changeâ procedures but then seeks to reverse courseâwhose life ended abruptly after suffering severe complications from a gender-related genital surgery. What led Yarden to adopt a transgender identity in the first place? In 2014, after encountering the growing wave of pro-trans narratives in popular culture, Yarden told his family that he believed he had a âfemale brain.â Though initially uncertain, his mother was ultimately convinced by scientific papers that suggested that her son could have a female brain trapped in a male body, and that this mismatch caused him unimaginable distress.
âA trans woman (such as myself) was born with a male body, but she has always had her female brain. Literally born with a female brain,â Yarden wrote in 2016.
This belief was widespread back thenâand it still is. On January 31, Wisconsin Public Radio featured an interview with a mother, Carri, concerned about President Trumpâs new executive order banning federally funded medical and surgical âsex changeâ procedures for minors. Carri spoke about her daughter, who identified as transgender at 15 and was allowed to medically transition. She said, âThose hormones really helped match his brain with his body which, to me, thatâs just the basic level of care we can provide individuals that identify as trans.â
The power of this narrative in persuading people to pursue, or to allow their children to pursue, irreversible medical procedures cannot be overstated. But the notion that males can have âfemale brains,â and vice versa, rests on a flawed interpretation of âbrain sexâ studies that in no way demonstrate or even suggest a definitive biological basis for âgender identity.â Little effort has been made to correct this misleading assertion.
The theory is advanced for relatively straightforward reasons. Civil rights lawyers, activists, and researchers contend that people who identify as transgender possess a âbrain sexâ misaligned with their physical body, thereby establishing a biological basis for âgender identityâ akin to immutable traits like race. This framing carries significant legal weight, as U.S. civil rights law offers strong protections for characteristics considered âinnateâ or rooted in biology.
In courtrooms, prominent gender clinicians routinely invoke âbrain sexâ literature to bolster the perceived immutability and innateness of âgender identity.â For example, Daniel Shumer, a pediatric endocrinologist and clinical director of the Child and Adolescent Gender Clinic at Mott Childrenâs Hospital at Michigan Medicine, provided expert testimony in a case challenging Texasâs prohibition of âgender-affirming careâ for minors. He linked âgender identityâ to âbrain structures,â arguing:
Scientific research and medical literature across disciplines demonstrates that gender identity, like other components of sex, has a strong biological foundation. For example, there are numerous studies detailing the similarities in the brain structures of transgender and non-transgender people with the same gender identity.
Such statements have become standard in legal battles over âgender-affirming careâ and other trans-related policies. In Talbott v. Trump, a legal challenge to the presidentâs executive order barring transgender individuals from military service, Nicolas Talbottâa transgender-identifying female and activistâjoined six active-duty service members and two prospective enlistees in arguing that â[s]trong research supports the conclusion that gender identity has a biological basisâ and that âtransgender women and non-transgender women have similar brain structures, specifically in the volume of the bed nucleus of the stria terminalis.â
Outside the courtroom, the idea of a brain-body mismatch has permeated popular culture, resonating with the âborn this wayâ narrative embraced by many in the LGBT community. Mainstream television and other media have reinforced the concept. For instance, in a 2009 episode of Law & Order: Special Victims Unit, psychiatrist George Huang, played by B.D. Wong, explained that a trans-identified boy had a âfemale brainâ: âFor some children, something happens in utero where the brain develops as one gender and the body the other.â Childrenâs books have reinforced this idea, with the trans-identified protagonist in I Am Jazz declaring, âI have a girl brain but a boy body. This is called transgender. I was born this way!â
There is reason to believe the âbrain sexâ narrative has influenced many young peopleâs decisions to pursue medical transition. In a forthcoming survey conducted by coauthor Buttons, 49.2 percent of detransitioner respondents recalled health-care providers framing the respondentsâ transgender identity as a brain condition, using phrases like âmale brain in a female body,â or vice versa. In total, 85.7 percent of those surveyed said that their providers characterized transgender identity as an inherent, biological trait that required medical intervention.
To bolster these claims, providers often cite a growing body of scientific literature that purportedly validates the brain-body mismatch hypothesis. These studies claim that the neuroanatomy of people identifying as transgender more closely resembles the brain structures typical of the sex with which they identify, relative to non-transgender-identifying controls. Media amplified these findings, often presenting them as definitive proof that trans-identifying people âare who they say they are.â Headlines such as âScience Proves Transgender People Arenât Making It Upâ and âTransgender people are born that way, a new study has foundâ further entrench the narrative.
Proponents of these studies, however, rarely possess the expertise and background knowledge needed to examine their methods and conclusions critically. And the culturally charged atmosphere surrounding transgender issues means that facts often take a backseat to politicallyâand legallyâexpedient narratives.
The central flaw in current research purporting to validate the cross-sex brain hypothesis is an inconsistentâor complete lack ofâcontrol for individualsâ sexual orientation. Why does this matter? Because most people who identify as transgender are not exclusively heterosexual, and same-sex attraction has been linked to neuroanatomical differences that reflect a cross-sex shiftâor, more broadly, to a reduction in typical sexual dimorphism (i.e., to having more androgynous brain structures). This raises serious methodological concerns about the extent to which sexual orientation might confound or interact with the neurobiological markers that âbrain sexâ studies routinely attribute to gender dysphoria. It also raises major ethical concerns about the use of âgender-affirming careâ as a form of gay conversion therapy or as a maladaptive coping strategy for gay men.
If one properly controls for sexual orientation, the reported neuroanatomical shifts in transgender brain-scan studies diminish greatly or vanish entirely. To illustrate that point, consider three influential studies examining regional gray matter differences between transgender-identifying individuals and controls. These examples, considered together, illustrate a pervasive problem in the âbrain sexâ literature.
The first study, by Lajos Simon et al. and titled âRegional Grey Matter Structure Differences between Transsexuals and Healthy ControlsâA Voxel Based Morphometry Study,â reported that trans-identifying individuals exhibit brain structures more closely resembling those of the opposite sex, relative to controls. This study is frequently cited as evidence supporting the brain-sex hypothesis. However, a different study by Eileen Luders et al. titled âRegional gray matter variation in male-to-female transsexualism,â which used similar neuroimaging techniques, found no significant differences overall in gray-matter volume between male-to-female (MtF) trans-identifying individuals and male controls. In one small brain region, the putamen, the MtFs did exhibit a cross-sex shift, relative to their datasetâi.e., putamen volumes in MtFs were larger and more similar to female controlsâbut this result is anomalous and incongruent with the findings of large-scale studies and meta-analyses demonstrating that males, not females, have larger putamen gray-matter volumes, on average.
A third study, by Ivanka Savic and Stefan Arver titled âSex Dimorphism of the Brain in Male-to-Female Transsexuals,â comprehensively analyzed structural brain differences using MRI. While the authors observed some structural differences in the brains of trans-identifying men compared with those of non-trans-identifying male controls, these differences did not align neatly with a feminization pattern. Instead, the variations were distinct from typical male or female brain structures, suggesting a unique neuroanatomical profile rather than a simple cross-sex shift. Importantly, Savic and Arver controlled for participantsâ sexual orientation and found that, when they did so, the brain differences attributed to gender dysphoria were much less pronounced.
A clear pattern emerges when comparing these and similar studies: the magnitude of the cross-sex shift reported in trans-identified individualsâ brains correlates with the proportion of homosexuals in the sample. For example, in Simon et al.âs study, all transgender participants were homosexual, potentially amplifying participantsâ sex-atypical neuroanatomical features. In contrast, Luders et al.âs cohort had a much lower proportion of homosexual participants, coinciding with null findings overall regarding brain feminization. Savic and Arverâs rigorous control for sexual orientation further demonstrates that some neuroanatomical differences previously attributed to gender dysphoria likely reflectâor are confounded byâsexual orientation-related brain variations.
Popular âtransgender brainâ studies, in short, often fail to control for sexuality, undermining the claim that people with transgender identities have brains that more closely resemble those of the opposite sex.
What would it mean if the âtransgender brainâ hypothesis were true, and properly controlled studies did document a statistically significant cross-sex shift in the brains of people who identify as transgender? It would not logically follow that a brain scan can capture a personâs âgender identityââjust as brain scans cannot ascertain a personâs sexuality. Differences in group averages do not mean that every individual within a group shares those characteristics. Populations contain variance; for instance, some straight men exhibit brain structures that skew feminine, while some gay men exhibit brain structures that skew masculine. Brain scans therefore cannot verify whether a person is homosexual; nor could they verify whether a person âis transgender.â Brains, like most physical traits apart from primary sex organs, are not discretely sexed; they simply exhibit average differences between the sexes.
Even if there were compelling evidence for âbrain sex,â gender clinicians, though often expressing strong confidence in the hypothesis, would be the last to advocate for the use of objective brain scans to validate their claims. Their hesitancy has roots in the history of sexuality research. When scientists proposed the existence of a âgay brain,â many gay rights advocates strongly objected, citing its potential for eugenic abuse (imagine, for example, a drug company developing a fetal âtreatmentâ to âcureâ homosexuality based on such findings). Despite progressivesâ deep pessimism about scienceâs potential for abuse, however, many activists still peddle the âbrain sexâ narrative.
Notably, even though homosexuality is associated with a cross-sex shift in certain brain structures, activists avoid claiming that gays and lesbians exhibit a brain-body mismatch. This avoidance highlights a striking inconsistency in the application of the âbrain sexâ narrative. For decades, research has shown that homosexuals exhibit subtle neuroanatomical differences that trend toward patterns typical of the opposite sex. Yet, proponents of LGBT rights have rejected the notion that these differences imply a pathological misalignment requiring medical correction.
The persistence of the âbrain sexâ narrative has real and sometimes tragic consequences. For individuals like Yarden Silveira, it contributed to life-alteringâand ultimately life-endingâmedical decisions based on a flawed understanding of the science. The notion that transgender identity is rooted in immutable brain structure has led countless young people to undergo unnecessary and often harmful medical treatments, frequently without fully informed consent or consideration of alternative approaches. Challenging that notion isnât just an academic exerciseâitâs a necessary step toward protecting vulnerable individuals from medical abuse.
Policymakers should mandate rigorous, independent reviews of the scientific claims surrounding transgender identityâs supposedly biological basis. This review should include scrutinizing studies that promote the âtransgender brainâ hypothesis, and incorporate evidence from desistance and detransition research, which highlight how transgender identities are often transient.
Public-health policies must be grounded in comprehensive and unbiased research. Otherwise, vulnerable young people will continue to face irrevocable and potentially devastating treatments.
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It's funny how there are supposedly no differences between males and females when it comes to sports, and yet there are supposedly MRI-detectable "male brains" and "female brains."
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This ideology is completely incoherent.
It's astonishing how many formerly reputable scientific institutions have embraced abject pseudoscientific gobbledygook.












