Evaluarea colegială constată că afirmațiile despre „sexul creierului” se bazează pe statistici defectuoase

Metode defectuoase și concluzii exagerate privind „sexul creierului“: o evaluare colegială a lui Kurth et al. (2022)

Comentarii și analize Sex, biologică și sport

Authors: Colin M. Wright, Adam M. Rochussen, Samuel G. Stagg
Journal: Theory and Society
Year: 2026
Source: link.springer.com/article/10.1007/s11186-026-09747-2

Summary

A widely cited 2022 brain-scan study by Kurth and colleagues reported that the brains of 24 transgender women, before hormone treatment, fell between those of men and women, though closer to men. This 2026 critique argues the key difference from men only looked real because of lenient statistical choices: testing in one direction only, and not adjusting for making three comparisons. With standard adjustments, the difference from men could easily be chance, though the difference from women still holds. Small groups and one unusual result make it fragile. Sexual orientation, known to relate to brain structure, was never analysed though the data existed. The critique is plausible but uses only published figures, was accepted nine days after it was sent in, and its lead author is a Manhattan Institute fellow on the journal's advisory board.

Key findings

Studiul din 2022 a comparat 24 de bărbați, 24 de femei și 24 de femei transgender încă fără hormoni, folosind un model computerizat care notează creierele pe o singură scală de la masculin la feminin. A concluzionat că creierele femeilor trans erau deplasate dinspre sexul lor la naștere spre identitatea lor de gen.
Studiul a testat diferența doar într-o singură direcție. Testând ambele direcții, așa cum este obișnuit, diferența-cheie dintre femeile trans și bărbați devine mai slabă. Ajustând pentru faptul că s-au făcut trei comparații, ea ar putea fi ușor întâmplătoare.
Diferența mai mare dintre femeile trans și femei s-ar menține și după aceste ajustări. Așadar, disputa este despre dacă creierele femeilor trans diferă de ale bărbaților, nu despre dacă diferă de ale femeilor.
Cu doar 24 de persoane pe grup, mărimea oricărei diferențe este instabilă. Un rezultat neobișnuit din grupul bărbaților nu a fost verificat niciodată prin reluarea analizei fără el.
Testul folosit de studiu pentru a justifica metoda sa statistică este slab la grupuri atât de mici. Criticii spun că ar fi trebuit raportate cel puțin și metode care fac mai puține presupuneri.
Dintre cele 24 de femei trans, 6 erau atrase de bărbați și 18 de femei. Orientarea sexuală este legată de structura creierului, iar autorii originali aveau aceste date, dar nu le-au luat în calcul.
Fiecare critic a cerut în mod repetat datele originale și nu a primit niciun răspuns, așa că critica se bazează pe cifrele publicate. Ei cer ca datele să fie făcute publice și ca studiul să fie repetat de alții.

Abstract

Kurth et al. (2022) concluded that the brain anatomy of transgender women is shifted away from their biological sex and toward their gender identity. We evaluate whether the study’s evidence supports this conclusion by focusing on its statistical methods and treatment of sexual orientation in its analyses. The principal finding relies on a very small sample, a weak justification for parametric analyses, one-tailed post hoc tests, no correction for multiple comparisons, and limited robustness testing. The study also did not properly account for sexual orientation as a potential neuroanatomical confound despite having the relevant participant data to do so. These methodological choices consistently bias the results toward smaller p-values and stronger apparent support for the authors’ stated hypothesis. The evidence presented therefore does not justify the study’s headline conclusion.

Conclusion

The analyses presented do not adequately support the paper's headline conclusion that transgender women's brains are shifted toward their gender identity. The evidence used to support that conclusion is weakened by a series of methodological limitations and poor choices, including a small sample size, parametric statistical methods, one-tailed post hoc hypothesis tests without correction for multiple comparisons, and the absence of several robustness analyses. The study also does not address sexual orientation as a potential confound, despite the authors possessing both the neuroanatomical and sexual orientation data needed to evaluate this possibility. These methodological choices and omissions consistently strengthen the perceived support for the authors' stated hypothesis while weakening confidence in the reported findings. Given the paper's unusually broad influence in neuroscience, medicine, journalism, law, and public policy, the methodological issues warrant careful consideration before the study can be cited as evidence supporting the hypothesis, and the authors welcome a response from the original authors and encourage public release of the anonymized participant-level data so that the findings can be independently replicated and evaluated.

Methodological limitations

No new data or re-analysis: The critics could not get the original data, so they cannot show whether accounting for sexual orientation or removing the unusual result actually changes the finding. These points remain ideas, not proof.
Which adjustment to use is debatable: The adjustment the critics apply for multiple comparisons is a strict one. The original authors stated in advance which direction they expected, which some statisticians accept as a reason to test in one direction. How much weight to give the adjusted result is a judgement call.
Narrow focus: The critique looks only at this one 2022 study. It does not cover the wider brain-scan research on transgender people, which includes larger studies with mixed results.
Only checks the statistics: It does not judge the computer model itself (what it was trained on, or whether a single 'brain sex' scale makes sense) or how the brain scans were processed, which the critics set aside 'for the sake of space'.
Very fast review: The paper was received on 19 August 2026 and accepted on 28 August 2026, an unusually short time for checking by outside experts.
Author ties to the journal and a think tank: Lead author Colin Wright is a Manhattan Institute fellow, has been paid as an expert witness on sex and gender identity, and sits on the journal's advisory board (he says he was not involved in handling the paper). The Manhattan Institute paid the fee to make it free to read.
Published in a sociology journal: It appeared in a sociology journal rather than a brain science or statistics journal, where specialist reviewers might have looked harder at the brain-scan methods.
No reply yet: Kurth and colleagues had not published a response at the time of review, so the critique has not been tested in debate.

detrans.ai

Summary

Key findings

Abstract

Conclusion