From Christina Buttons’s  Substack:

Here’s why it’s wrong

The majority of the studies on the “transgender brain” have a fatal flaw: they didn’t control for confounding variables like cross-sex hormone use and, most importantly, sexual orientation. When a study doesn’t control for confounding variables, it means that the researchers did not take into account other factors that could have affected the results of the study, which make it difficult or impossible to determine whether the relationship between the two variables being studied is truly causal or a byproduct of other unrelated factors.

Cross-sex hormone use can have effects on the brain, including changes in brain structure and function. But more importantly, many trans-identifying individuals are same-sex attracted, so the research on the “transgender brain” claiming to find structural regions that resemble the opposite sex are essentially rediscovering findings on the “gay brain” and reinterpreting the results to fit their preferred conclusion.

In the early nineties, neuroscientist and author Simon LeVay made the breakthrough discovery that the brains of homosexuals had structural differences that resembled that of straight members of the opposite sex. So it seems that while undertaking the hunt for the “transgender brain,” researchers have forgotten all about the discoveries made about the brains of same-sex attracted people.

The first “brain sex” study that did take into account the participants’ sexual orientation found that the brains of transgender individuals were similar to those of people of the same birth sex rather than the opposite sex.

When researchers scan the brains of heterosexual people who identify as transgender, they also find they are typical for their natal sex. Samuel Stagg, a U.K.-based Ph.D. student of neuroimmunology, explains: “The homosexual sub-group show brains skewed along the male-female dimension. However, this is predominantly due to their co-occurring homosexuality. When we scan the brains of the heterosexual type, we find they are more typical for their natal sex.”

“Gender identity” not gender dysphoria

Gender dysphoria, like other psychiatric conditions, may have some biological underpinnings. There are traits like neuroticism that can predispose people to psychiatric conditions and research suggests that neuroticism has a strong biological basis with both genetic and environmental factors contributing to its development.

But gender activists are not concerned with gender dysphoria, rather they aim to establish a biological basis for being transgender that ceases to categorize it as a mental illness. Activists have pushed for a more “inclusive” definition of what it means to be transgender that seeks to reduce stigma and perceived barriers to medical transition services.

After the legalization of same-sex marriage in 2015, civil rights and gay rights organizations that may have otherwise had to shutter their doors pivoted to championing “trans rights.” The success of the “born this way” campaign in promoting the idea that sexual orientation is an innate, immutable aspect of identity has prompted activists to also present being transgender as innate and immutable.

Manhattan Institute fellow Leor Sapir wrote his Ph.D. dissertation on the rapid proliferation of the “transgender rights movement” and its efforts to obtain civil rights jurisprudence for “gender identity.” To this end, they have attempted to prove that “gender identity” is an innate, immutable trait called “neurological sex” or “brain sex,” which they say should override natal sex.

“In the American civil rights tradition, if you can convince a judge that being transgender is like being black, then you can tap into this entire body of judicial precedent and civil rights laws that immediately applies and gives you all the policies you want,” Sapir told me. Leor Sapir has written a number of important articles on this topic for City Journal, be sure to read them for further understanding.