Let me explain: (This is actually a very good question. )
The two genders are not statistically equal in capability. Neither are the races. ( ethnic groups if you wish, if you believe that a 'race' cannot be easily defined).
Remember, we are talking statistics not about individuals ( just like stating that men are taller than women, you will find a some women to be taller than some men).
Now you might ask why this is important, to know this fact especially since we are talking statistical probability rather than about individuals? Well a typical sexist, (the way I understand ho