In some of my ongoing games, I don't bother to check off a preferred skill for the kids. They may start with something, but usually only one (except if I used a kid to help cure someone.)

But eventually most will become adept in Farming and Building.

In the game where I purposely train everyone to (in order) Building, Healing, Farming, Breeding (women only) I'll sometimes get a villager who refuses to learn any building skills!