The higher number of men in senior positions isn't necessarily sexist. I think it's because men are more likely to accept insane work-life balance in exchange for the status, because it increases their attractiveness more than it does for women. A women who is a CEO is not much more attractive to a man than a women who is a dental hygienist; however, a man who is a CEO is much more attractive than a man who is a welder. Take it as sexism or not but lots of men are hellbent on getting that high-status, high-stress job.