I think that's is what makes this game great. Just like in real life, some villagers are lazy, some are hard workers, and some just want to play all day.

Also, if you breed using a master builder, chances are better that your infants will be pre-disposed to be builders. The same holds true for farmers, researchers, etc. After your infants are done nursing, check their details screen and most will already have a small disposition for one skill or another.

I don't want to write too much, because figuring all of this stuff out is what makes this game really enjoyable.