As Brian Leiter notes, there’s a very interesting discussion over at Sappho’s Breathing about the relationship between the relative prominence of certain disciplines within philosophy and how gendered (or otherwise) those disciplines are.
I mostly want to just recommend those discussions, but let me make one distinction that I think is getting blurred over there. The further we get from positivism, the less and less reason there seems to be to view metaphysics and epistemology as anything like a single discipline. Of course there are connections between the two, but really not much more than between any two large fields in philosophy. From where I sit, that looks like it matters to this debate.
(Warning: the following contains generalisations from a ridiculously small sample, and unscientific observation to boot.) Among my peers, there isn’t that much of a gender gap amongst philosophers working in metaphysics, or philosophy of language, or ethics or (I think) philosophy of mind. There is, however, a noticable gender gap in epistemology still, even among the younger generation. Now this could be a sample size phenomena, and it could be due to the fact that I’m looking at a rather non-random sample. If it’s a real phenomena though, it’s kinda surprising, because I would thought that whatever features of logic and philosophy of language and philosophy of science and metaphysics and so on made them gendered male were less prominent in epistemology, rather than more. Of course that’s the kind of question about which I’m absolutely not an expert, so I’ll defer entirely to more learned opinion on it.