Independent thought and parenting

[Corbin Wells]

I am hoping to write a book on this and decided to get some more info before I even think of typing up anything just yet.
Here's the idea: People grow old and die and have kids to take their place and whatnot. The parents job while raising the child is to keep their own beliefs going by teaching their child every belief that the parent has. But here's the question:
When should the parent let go of their teachings and let the child decide for themself? When should the child be granted the right to become an independent thinker? When does the parent no longer have a say in what this child should be? (I know it's a little sloppy right now)