More egalitarianism should be favorable to women /if/ you assume a priori that they are mostly disadvantaged through lack of access to education/resources, and the real expected outcome distribution is 50-50.

If you assume that there are underlying differences in interests and aptitude, more egalitarianism allows these differences to be expressed more since women are more free to eg. choose a career working with people, like medicine or law. http://www.thejournal.ie/gender-equality-countries-stem-girl... It also raises the bar for inherent aptitude to get into/(the top of) a career, since you're competing against a much wider pool of talent.

The point I was making to the parent was that his point "cross-generation drop in ratio proves it's cultural" doesn't hold up, because there have been many changes across those generations, you're comparing apples to oranges.