All the parent comment is really saying is that "young, childless women" aren't an equivalent demographic to "young, childless men." In addition to the argumen

All the parent comment is really saying is that "young, childless women" aren't an equivalent demographic to "young, childless men." In addition to the arguments already stated, I imagine that more men than women in the relevant age group are childless in the first place (since men are typically older than their wives). This alone means that a young woman's childlessness says more about her than a young man's does about him. Nowhere does the comment say that women should be earning more than men. It says that if having children wasn't as much of a liability to working women as it currently is, then childlessness in women would be less associated with career-mindedness, which would cause this particular statistic to equalize somewhat.