Right - so imagine that you didn't have that opportunity to do that academic work because you have an elderly parent at home who needs care. You've got two little kids at home who aren't yet school age and thus needs care. You wouldn't be content with your work situation in that case, right? Sure, it might just be for a few years - but what if those few years block you from key promotions or research opportunities? Do you get it? I'm certainly not saying that everyone should be focused on their careers, I'm just observing that sometimes people are making tradeoffs between their careers and their personal life, and more often than not it is the female in the heterosexual relationship that is making more of those tradeoffs.