Maybe if they played together instead of separately things would change, considering how it is played and what the logic employed entails. You might not know how to deal with en passant if you've never seen it used.

Girls are made to feel unwelcome in chess environments at a very young age. Of course once many drop out because of cultural pressure, the remaining small sample size will have less spread than the larger population of men who have been made welcome in chess environments their whole lives.