brains are not wired to be male or female, and brain sex is a myth

Sex differences in the adult human brain: Evidence from 5,216 UK Biobank participants

“There were very small correlations between brain variables and the cognitive tests, and these associations did not differ by sex (consistent with a prior meta-analysis on thelink between brain volume and intelligence [49]). Mediation modelling suggested that, for verbal-numerical reasoning, a very large portion (up to 99%) of the modest sex difference was mediated by brain volumetric and surface area measures. Smaller fractions (up to 38%) of the modest link between sex and reaction time could be explained by volume or surface area.”

From an article about the study:



“….there do appear to be many differences between male and female brains, but there’s also tons of overlap. The obvious question, when it comes to sex-based brain-structure differences, is whether they are the cause of behavioral differences. Differences alone don’t necessarily explain anything:

If women are socialized to act differently than men from a very young age, this could lead to different sorts of brain structures, especially in a set of brains whose owners are all middle-aged or older.”

Analysis of Human Brain Structure Reveals that the Brain “Types” Typical of Males Are Also Typical of Females, and Vice Versa



“We have recently discovered that most human brains are composed of unique mosaics of features, and concluded that human brains do not belong to two distinct types, “male” and “female,” and that one’s sex category provides very little information about the specific composition of one’s unique brain mosaic (Joel et al., 2015). The present study supports these conclusions by showing that even when biological relevance is ignored, the structure of human brains does not fit into two distinct types of brain, one typical of males and the other typical of females.”

Incorporating Sex As a Biological Variable in Neuropsychiatric Research: Where Are We Now and Where Should We Be?



“That sex effects may be context dependent also means that one cannot easily generalize from a single study to other conditions and other species.”



Sex Differences and Opposite Effects of Stress on Dendritic Spine Density in the Male Versus Female Hippocampus



“I realized that if certain areas of the brain could change from the typical ‘female form’ to the typical ‘male form’ under stress, there wasno point in talking about the female brain and the male brain,” Joel told Haaretz (paywall).

Men and women are from Earth: Examining the latent structure of gender.



“Average differences between men and women are not under dispute, but the dimensionality of gender indicates that these differences are inappropriate for diagnosing gender-typical psychological variables on the basis of sex.”

why do trans people sometimes have these brain features that are inconsistently found to be prevalent in the opposite sex? because of the same reason those brain features are found in anyone of any sex and any gender identity: socialization!

Transsexualism: A Different Viewpoint to Brain Changes



“we may predict that related brain changes result in human adaptation to specific sociocultural environments…He/she imagines himself/herself in his/her preferred gender identity rather than his/her biological sex, and thus tries to adapt his/her values, lifestyle and behaviors to his/her gender identity. Therefore, a subject with GD tries to experience life in his/her preferred gender identity and skews from his/her biological gender and normal culturally contextualized behaviors every day. Depending on how much the subject with GD persists in changing his/her gender (i.e., positive, neutral or negative transgenders) and the extent to which he/she has experienced gender identity, we will observe brain changes and, as a result, related culturally voluntary behaviors.



In general, an overview of brain morphometric and neural activity findings in transgenders demonstrates contradictory results, which cannot reflect masculinization or feminization of the transgenders’ brain"