I can totally agree. Humans are most fertile around early twenties, but as a young (23) parent I'd say it is not the best age to actually raise children.

We're impatient. We have much "explosive" energy, the kind not really suitable for watching a newborn for hours.

We can now have beautiful and very healthy babies easily, but Grandma is way better sitter than us for most of the day - more experienced, more calm, comfortably retired by now :) And I do belive it is the natural way. Better than kindergarten.