According to this New York Times story, less than 15% of Wikipedia contributors are female. This imbalance may be due to "the traditions of the computer world and an obsessive fact-loving realm that is dominated by men and, some say, uncomfortable for women."
A "participation rate of roughly 85-to-15 percent, men to women, is common" among contributors to “public thought-leadership forums". It is thought that women possess less confidence to assert their opinions than men do. This may be especially true in situations where women are a minority, so one group advocates "recruiting women as a group to fields or forums where they are under-represented. That way, a solitary woman does not face the burden alone." Similar to women going to the bathroom in restaurants?
Apparently, this gender imbalance developed as a result of Wikipedia "letting things develop naturally." Speaking of things developing naturally, I couldn't help but smile at Richard Whitmire's comment on this story: