I have read that there may be some structural and chemical differences between the male and female brains. There is still more study needed as scientists don't agree on the importance of any differences, even if they accept them; we were told in Psychology class, that the Corpus Callosum on females may be comparatively larger than that of males. This part of the brain aids in transferring data between right and left hemispheres. Our teacher says this may be an evolutionary development that allows the average male more intense narrower focus to aid his role as protector/hunter, and females as the gatherer, childbearer, etc has a broader focus aimed at juggling multiple tasks.

There may be other factors -like hormones- but my point is that we may be geared in such a way that each sex has a few extra ability points in some fields, or a little more interest in certain topics, based on our wiring. I don't think this means one is better than another, this is just like someone who has a natural talent for music and someone who has to work hard to develop musical ability. Our brains create neural pathways based on how we use them so a female interested in math/science -even if we assume the lesser ability or inclination thing is true- can develop greater ability through her application.

Ethnicity, culture and many other factors add or detract to these abilities.

For me women are 4 quarters, men are a dollar bill. Different physical attributes, equal value. As a married guy of 20 years I can tell you that while I am stronger and more capable than my wife in some areas, she far surpasses me in many many others.