Very few men lactate, that is absolutely true. However, in our family it is the mother who has the drive and career ambitions, which is why the child has fallen asleep on the father instead, including when said child was but a few months old and the mother had a six-week business trip abroad.

I am sure children benefit from having several parents and role models, but I am not so sure that the shape of the genitals matter as much as whether the parent(s) is/are emotionally in tune with the child. The classical father of yore was simply not much of a parent. Today's can choose either.