Nature? most people neuter their pets.
Christian homes? In name only. Come on, this hasn't been a seriously christian country since, desegregation or roe v wade take your pick.

On the one hand yes, these people are getting what they wanted. On the other hand, lets not pretend the average american was offered a deal and picked poorly. We weren't born into a healthy society.

To whit, your last point. A man and his wife in American for the last 4 generations do not have children, they have a child when they are ready and finacially stable and they've accomplished enough of their goals to fulfill their egos. That's what the average american grew up with.