Not a surprise to anyone who has been paying attention. 1. The great Thomas Sowell addressed this directly in the long long ago (1980s?). His challenger report

Not a surprise to anyone who has been paying attention. 1. The great Thomas Sowell addressed this directly in the long long ago (1980s?). His challenger reported a discrepancy in remuneration for women over 40. He correctly identified an additional dimension: never married. 40+ never married women experienced no income discrepancy. 2. The recent resurgence of this issue has been debunked, most notably to my knowledge by feminist economist Christina Hoff Sommers. Again, it's as simple as child rearing. Suitably terse explanations from ReasonTV and PragerU may be easily found on YouTube.