You didn't intend saying this, but what your flippant remark amounts to is that sexism has been the rational answer to the facts of human biology for almost all

You didn't intend saying this, but what your flippant remark amounts to is that sexism has been the rational answer to the facts of human biology for almost all of human history, and that even today, given the advances in reproductive technology sketched in my post above, it's far from clear whether 'sexism' isn't still a good or at least reasonable division of labour. This sits uncomfortably with the everyday meaning of the term.