I was just having dinner with a female friend that was an EECS major (electrical engineering computer science) from UC Berkeley and she brought up another point. She said whenever she took classes and needed a partner, she'd always have guys come up to try to help her and that usually they were among the smartest guys in the class.

As far as the marriage/kids issue goes ... I think I read that the average age of the people at YCombinator is 26; and as far as my own observation goes, that's right around the time that my female friends started seriously thinking about the marriage/kids issue. I think the discrepancy is really driven by the biological clock. Men can have kids well into their 50's, but it's pretty dangerous for women to have kids past 40.