Here’s an interesting article relating to sexual differences: Genes Organize Male, Female Brain Differently. Actually, the findings presented—that there are genetic differences between male and female brains—don’t seem at all surprising. After all, men and women differ genetically almost as much as chimpanzees and homo sapiens, there’s a whole chromosome’s worth of difference, so why not expect to find that their brains differ genetically? Nonetheless, it appears from the article that since the 70s there’s been a sort of dogma that the differences were entirely due to differential hormone exposure in utero (and were thus in a sense environmental), a dogma that has now been refuted.
Still, the cause of PC soldiers on: the only difference between male and female brains the article mentions is one that seems to make it easier for women to articulate their feelings, and in its very first sentence it says that the findings undermine “the notion that homosexuality and gender dysphoria [the belief that one has been born in a body of the wrong sex] are matters of choice.” In fact, all the rest of the article does is quote the speculations of some scientist at the David Geffen School of Medicine to the effect that although hormones don’t explain such conditions it’s possible some genetic condition might.
For those unfortunate enough to read the New York Times, the article also gives some statistics on sexually ambiguous babies that (as I recall) are about an order of magnitude lower than the ones Natalie Angier offered in a several chirpy little articles she wrote about how gender is socially constructed because there are lots of ambiguous babies who have to be made male or female by surgeons.