Well there's one massive factor, at least until the kid is weaned, the mom is the easiest food supply for the kid. It's vastly easier than pump and bottle or ev

Well there's one massive factor, at least until the kid is weaned, the mom is the easiest food supply for the kid. It's vastly easier than pump and bottle or even formula and bottle. Beyond that phase though it's true it's mostly societal, once the kid is eating real food there's little reason for a particular parent to be the primary care giver.