It's an interesting topic. There is no doubt that there are sociological and biological differences between the genders. Men obviously have higher levels of testosterone, and that can lead to more aggressive behavior. I think that has a little to do with it. Poker, particularly NL, frequently rewards those that take risks. Males also have higher scores in mathematics on standardized tests. That doesn't mean that some females do no have great mathematical abilities. Just, in general, males have an advantage.
And if males are not considered superior poker players, why would there be separate events for women? I wish they would eliminate the separate events. Women can and will do as well as men some day. There are others strengths they have that can make up for any genetic disadvantages. BTW, the highest ever recorded IQ score was by a women named Marilyn Vos Savant.