I believe that's pretty much a BS contrivance of politicized "science," meant to serve the pervert political agenda. There is no such thing as a "female brain" inside of a male.
The research was done twice, first in the 1960s, by top researchers (one of whom I knew), then again in the 1980s, by the USG. Both times there was a very real concern that the use of plant estrogen, very chemically similar to human estrogen, by farmers, and other industrial chemicals, could interfere with this process, perhaps creating a generation of androgynous males.
The research itself was very detailed. Finding what chemicals could block the testosterone or mimic it, the lack of it reaching the brain of male test animals, or introduced to female test animals. They went so far as to provide it to just one hemisphere of the animals brains, and not the other. The same tests were conducted hundreds of times with the same result.
Importantly, in animals, this does come close to dictating their sexuality, since they have little gender identity that is not impulse driven. So males would act with female behavior to attract other males, and females would try to mount other females.
Those with divided brains exhibited both sexual behaviors, willing to mount or be mounted.
However, the research also showed that humans sexual attraction is far more complex than animals. Though human males would have slighter frames and a more androgynous appearance, the rate of heterosexuality was about the same. Women seemed divided on their attraction to more masculine or less masculine males, both by their personal preference, and by the time of their menstrual cycle.
Females with a “male” brain were more “tomboy” before adolescence, but were seen as *more* attractive to men as adults. However, by then, their serum testosterone level had more impact on their sexuality, if not their sexual orientation.