Well you can obviously teach them or have your children tutored for specific skills. I also assume you can use your kids once they come of age for labor on your farm or in your shore front.
You won't be able to manipulate their personalities but you can influence how they grow up. I don't think you'll need to make contracts with your kids for them to do stuff for you, hopefully you can should tell them to do something and they will.
Hopefully NPC kids arent all just carbon copies of each other, I'd like to be able to say "I like bill, bill does the chores while tim is always adventuring all day"