@Skyknight #170803
I think it probably had more to do with ancient life expectancy and maternal/infant mortality. If there's a good chance you'll be dead or at least very unhealthy by 35, in an agrarian society you need to start having kids as early as possible - because half of them will die in infancy, and mom will probably die in childbirth with kid 3, 4, 5 or 6. And you do want as many kids as you can have, because after a few years they're farmhands, and if you do make it past age 40 they're your retirement insurance. Those factors are easy to forget in an age when almost everyone gets old, few need to do farm labor, and Social Security exists.