This article from the San Jose Mercury News, Seeing the World from Both Sides, is worth a read:

When a Stanford University neurobiologist made a case this week that discrimination, not genetics, keeps women out of science, his comments carried more weight than usual.

Ben A. Barres spent most of his life — and his career as an accomplished scientist — as a woman. Only nine years ago did he complete the process of changing into a man; only recently, he says, did he begin to realize how bias holds women back.

Oddly enough, I just had a conversation about this with Bryan Monroe from work.  One point I’ve heard before that this article doesn’t make: girls in science classes often give up on further science if they don’t excel, while boys are encouraged to continue even if they do poorly.  That seemed telling to me, because it’s less about a specific person discriminating and more about internalized cultural bias.