Every age sort of has its own history. History is really the stories that we retell to ourselves to make them relevant to every age. So we put our own values and our own spin on it.
I don't think people who have children are acting selfishly or unselfishly. Having a child who'll be loved, to parents who love each other, is the important thing.
We think of medieval England as being a place of unbelievable cruelty and darkness and superstition. We think of it as all being about fair maidens in castles, and witch-burning, and a belief that the world was flat. Yet all these things are wrong.