While villagers will tend to exercise their "preferred" skill more than the others, there's no way to stop them from choosing to do any of the things that they know how to do. Even the instructions that come with the game warn about that phenomenon: "Male breeders will impregnate many women." That's why I always train only the women in breeding!

By the way, since the GC is only 5, he's not your culprit!