I've just started a new game. Both the starting children and the nursing mother are runners! To cap it all, I've just had my first event: it was the 'Long Legs' event, and so yet another villager has become a runner. That makes four villagers out of eight, including the babe-in-arms. Alas, I'll have to wait for the mother to drop her baby and for the two kids to grow up before I can really start gaining the benefit of all bar one of the runners.