This seems like a really long argument just to end up at the main point being: "It really is sexism". The light bulb moment here is that it's not necessarily sexism on an individual level but on an institutional one.

I believe there is an obvious difference men and women which, on a general level, incites women to weigh family responsibilities over career prospects. However, industrialized nations exacerbate that difference by making it very difficult for women with children to spend the time necessary for career advancement.

The key here isn't necessarily throwing your hands up and saying there's nothing you can do about it, but more robust programs for parents to help lessen the load of parenthood.