> higher-than-I-would-expect number of those kids have developmental problems

My experience is that when you start talking to parents, you'll find that there are very few kids who don't have some kind of "problem".

My friend group has a bunch of parents who had kids in their 20ies, and I don't know of a single kid that doesn't have some kind of "issue".

Also, from talking to a friend who is a therapist for children, she says that with a lot of children in therapy she thinks that it would be better if the parents went to therapy rather than the kids.