Having two children means repeating yourself at least twice as often as you did with only one. Children aren’t really expected to listen and follow instructions until about 30 months, but by then many couples will have already had a second. It’s a clever bit of evolution. Children who started ignoring their parents too early obviously didn’t survive long enough to pass on their genes. I mean, by the time the kid is two and a half, you might as well just keep it. You’ve already changed like 6,000 diapers. Dealing with that much excrement tends to harden a person.