I suspect you are right. Now that I think of it, I actually recall hearing a podcast on this (Planet Money? Freakonomics?) where they dissected the statement around women only earning something like $.75/dollar compared to men. I believe they found that if you looked at earnings before having a child, they were equal, and that the reduced earnings came from taking time off or sacrificing workload (and presumably total contribution) for flexibility. This then resulted in not advancing as rapidly as say, someone putting in twice the hours, or who did not take several years off and thus has that many more years career experience, despite being the same age.