Do trans people's brains actually resemble the brains of their experienced gender? Where does transexuality come from?

sigh

Yes, there is some evidence of brain differences between trans and cis people of the same birth sex. In at least some ways, trans people are closer to cis people of their same gender identity than cis people of their same original biological sex. More research needs to be done, and the exact cause is not well understood, but statistically, there appear to be some differences.

A few examples:

1

[We] determined in 42 subjects the number of somatostatin-expressing neurons in the BSTc in relation to sex, sexual orientation, gender identity, and past or present hormonal status. Regardless of sexual orientation, men had almost twice as many somatostatin neurons as women (P < 0.006). The number of neurons in the BSTc of male-to-female transsexuals was similar to that of the females (P = 0.83). In contrast, the neuron number of a female-to-male transsexual was found to be in the male range. Hormone treatment or sex hormone level variations in adulthood did not seem to have influenced BSTc neuron numbers. The present findings of somatostatin neuronal sex differences in the BSTc and its sex reversal in the transsexual brain clearly support the paradigm that in transsexuals sexual differentiation of the brain and genitals may go into opposite directions and point to a neurobiological basis of gender identity disorder.

2

In controls, males have significantly higher FA values than females in the medial and posterior parts of the right superior longitudinal fasciculus (SLF), the forceps minor, and the corticospinal tract. Compared to control females, FtM showed higher FA values in posterior part of the right SLF, the forceps minor and corticospinal tract. Compared to control males, FtM showed only lower FA values in the corticospinal tract. ... Our results show that the white matter microstructure pattern in untreated FtM transsexuals is closer to the pattern of subjects who share their gender identity (males) than those who share their biological sex (females). Our results provide evidence for an inherent difference in the brain structure of FtM transsexuals.

There are many more studies, if you want to look for them. The issue probably isn't black and white, and there are likely to be individual differences, but there do seem to be statistical differences between cis and trans brains in at least some aspects.

/r/askscience Thread