I've found myself in a similar position a couple of times with "advanced" games. Normally I try to ensure that I have at least two kids at all times, but on these occasions I was returning to a game that had been left on its own for a while. In each case there were a few babes-in-arms, but no kids running around.

Even when I have several million tech points and plenty of food I still try to pick up collectibles and mushrooms, to keep my hand in as much as anything. It certainly felt strange having to ignore those that popped up, although thankfully none of the missing ones appeared.