I think it still boils down to child rearing... In pretty much ALL societies across the world, the female parent is stuck rearing the children, even if the male decides to try something as foolish as trying to make a career playing music fulltime! Women, at least, have the sense to know that the child is going to need at least ONE full time parent, and should they decide to make music their career, it's going to be only the tiny, lucky few who will be able to rely on their male partner to raise the children while they go out at night (and day!) to play music...