A lot of the blogs I've been reading the last few weeks have been talking about female participation in the disciplines (and the associated blogging) of theology, biblical studies, religious studies and philosophy. Searching around I found this graphic (H/T Crooked Timber) of % PhDs awarded to women by academic discipline (in 2009):
That's interesting to me as I tend to think of philosophy and biblical/religious studies--content-wise--as akin to literature studies, the humanities or the social sciences. Again, content-wise.
So the gender divide would, I guess, seem to be cultural in nature. As to what those cultural issues might be I couldn't say.