One point I want to add: Throughout most of human history, it was economically beneficial to have lots of children. They were your retirement plan (and cheap labor).
In most developed countries, this is no longer the case. People who want children get one or two, just to scratch the itch, but that’s not enough to sustain the population (without migration).
It’s called displacement aggression The sportsball fan identifies with his team to the point that it feels like he lost the game himself. Since he can’t express his frustration and subsequent aggression towards the opposing team (since he is in front of his TV several 100km away), he expresses it towards the next best thing that is weaker and accessible, e.g. furniture, walls, wife and kids…