Fascinating and weird wrinkle to the wage gap conversation: Single women, married women, and single men all make about the same amount of money. It's MARRIED men who vastly out-earn everybody else. stlouisfed.org/on-the-economy… 
The researchers suggest this isn't because having a wife makes men earn more, but rather that high-earning men are more likely to marry. On the flip side, we also know that lower earnings by women are mostly driven by those with kids. nytimes.com/2017/05/13/ups…
So probably part of what's happening here is that married men are taking on more of the responsibility of financially supporting their growing families. Which, of course, there's no essential reason for them to do more than women. (Once they get past the childbearing part.)
