Prepare to be disappointed in your search. The science is very high-quality, it is just still evolving, but there is a lot of it. Part of the problem is that it is multidisciplinary, involving psychologists, medical professionals, geneticists, biochemists and other scientific disciplines. Each focuses on studies that fall within the realm of a given researcher’s expertise. Cumulatively, the data is becoming very clear that actually there is a biological difference between male and female brains both structurally and functionally.
Structurally, Harvard University pathologists started examining the brains of women, men and trans people a little over 30 years ago. They discovered that structurally, women’s brains have different sized putamens and gyruses and more pre-frontal cortex connections than male brains. There are other differences. But these are very real structural differences that affect the way that men and women think.
Functionally, it is objectively provable, both by psychological tests and by PET scans where men’s and women’s brains light up differently when subjected to various stimuli. Trans brains light up in the same way as the brains of the gender with which they identify. On a whole variety of psychological tests designed for little boys and girls to mature adults, where the sexes answer the questions differently, trans people answer them the same way as the gender with which they identify, not their sex assigned at birth.
The point is that there are very real differences in both the structure of men’s and women’s brains and the way that they function. Some of the function of course is related to the hormones to which they are exposed. Men and women produce different amounts of testosterone and estrogen and they also process them differently. The AR gene, which is responsible for processing testosterone, is longer in women than men, and does not react as strongly to the presence of testosterone as a man’s AR gene does. Among other things, it is well known that high levels of testosterone and sensitivity to it (since this is determined by how the AR gene processes it), results in a more aggressive personality. This is just one of any number of genes that affect human biology and psychology.
Human biology is complicated and it’s affected by a whole variety of things. Hopefully you are open minded. If you are, you’ll be surprised at what you find. There is a lot of research out there. The field may still be evolving, but there are decades worth of experience and studies investigating the very issue that you are skeptical about. We may still be learning and discovering new things, but we already know a lot, actually more than enough, to put to bed the misconceptions about trans people and differences between how men and women think.
