Maybe because men and women don't interact that much - or with a greater distance? There's two advantages:
1. I hate to recall how some of our female fellow students were treated by some of the male ones (geez, just because she is talking to you does not mean she's into you, I talked to you as well, and I'm not hitting on you either). The joke was on the males: droput rates were more than twice as high
2. they are maybe more encouraged by other females to do what they bloody want - or just less discouraged by stupid males (ok, there are just as many stupid mothers, telling their daughters stuff like "don't worry, I was bad in Maths as well").
I have been thinking and wondering about the gender imbalance. A lot. Interesting fact: there was about gender parity in Mathmatics. It also works in the reverse: there are not too many male kindergarten teachers, or elementary school teachers, or biology students.
What can we do? Try and expose our kids to all kinds of experiences and encourage them to try different stuff. It starts with us as parents, at a really early age. Encourage them! It is not a problem if a girl loves cars and the colour blue, and neither is it problematic if a boy likes pink fluffy unicorns!
All affirmative action, uh, actions past age ten or so are just actions and just try to treat the symptoms not the cause.