I just turned 41 and my son turns one in January. I can think of a million reasons to leave the city and in fact my wife and I are strongly considering it, but the necessary reliance on cars in the suburbs is an enormous deterrent. I’ve lived that way before, so I know what’s bad about it. We are probably only going to consider walkable small towns (as opposed to car dependent exurbia).
It's also true that people very, very commonly move to the suburbs once they have children, and it's not because those people are all morons.