Recently I've been thinking a lot about the difference between sex and gender. And it makes me wonder, "is this one of the subtleties that causes confusion about the women in cs issue?" But first, I suppose I should explain what I see as the difference between the two words/ideas, which understandably cause much confusion and are frequently used in the definition of each other. Sex is the biological condition of being male or female. (Already this is more complicated than I'm saying, since of course there are people who don't fix nicely into those categories based on their bodies or their chromosomes.) Gender refers to the set of characteristics that are associated with sex groups. So, "liking dolls" is a quality that is thought of as being gendered female. It does NOT mean that all women like dolls, or that all doll-liking people are all women. I like to think of it as a statistical correlation. And it does not and should not imply causation. Being a woman does not cause you to like dolls. (Believe me.)
And this is where Larry Summers went wrong. (You knew I'd get to him eventually.) He looked at the low numbers of women in the sciences and decided that it must imply that women (sex) do not have the intrinsic aptitude for the field. In other words, the smaller number of men who like dolls (or admit it) implies that men can't like dolls. They just don't have the intrinsic ability to like dolls (or the color pink, or cooking, or English literature, or...). Which is obviously ridiculous. Computer science is currently gendered male. There's a (strong) statistical correlation between being in computer science and being male. But gender is a socially constructed concept. So don't tell me that women (sex) just aren't as good at computer science as men or pretend that the current gendered norm means anything about a more permanent biological state.