Another important one: Transgender people's brains do not match the sex to which they identify with, a 2016 review of many studies into transgender brain structures: https://link.springer.com/article/10.1007/s10508-016-0768-5

Note: There does appear to be a certain brain phenotype associated with transgender people, but it's important to note this is after hormone treatment. Most of the studies in the review have post-hormone treatment subjects. There is one study in that review that did include pre-hormone subjects, concluded that "their data did not support the notion that the nonhomosexual MtF brain was feminized", although interestingly "the cortex of nonhomosexual MtFs presents morphological peculiarities in regions in which male and female controls do not differ."