Women's mental capacity is spread out more evenly than men's, who tend to have more members on the high end and the low end.
http://www.crewresourcemanagement.com/female-pilots
This is a pretty thoughtful discussion
The main point is, pilots are trained, not born
More important that gender is that people meet the physical mental and psychological profile to be a pilot. Men and women in general can have strengths in different kinds of brain functions (”intelligences”) but both kinds can be trained to be excellent pilots.
Despite the opportunities being more open (but still controlled by the reluctance to employ women in combat on a 50-05 basis with men) I would subject a guess there are far fewer women who WANT to be military or fighter pilots than there are men
For forward-thinking women it is not a career that is conducive to having a family life, since you peak with all your training at about the same time as your body peaks to have children
Plus you have to deal with sexist BS to prove yourself at every step of the ladder, and that can be an lonely and emotionally draining life
Given there is an element of altruism in choosing a service-to-others career, There are lots of ways to save the world. Half our medical students are female.