Doctor Kosofsky warned me that this was a controversial issue and that he would only state what he knew to be true. He wanted it understood that his answers, although enlightening me on the neurological aspects of the hypothalamus, should not be taken as an affirmation of any theories relating to homosexuality. He then confirmed that my recollection of the scientific bulletin was correct. It does appear that brains, at least the hypothalamus, are gendered. Quickly, I sent him another question regarding embryonic development of the brain.
Embryology teaches that early embryos all start out as female.
At some point in early gestation, if the chromosomes destine the fetus to be male, this female embryo is altered by the genetically programmed addition of certain hormones, called androgens. These androgens, especially testosterone, instruct the embryo to develop male characteristics. In their absence, the embryo continues to develop into a female. This inquiry received no definitive commitment from my learned friend at Harvard, but he did refer me to some studies where I could find the answer. In a paper published almost a quarter of a century ago, a research psychologist at Villanova University was also puzzled about gender.