So as Wally explained it, almost everyone says "tu", in both ways, parents to children and children to parents. It used to be different until like a century ago where in the wealthiest families parents and children would say "vous" to one another as a form of respect. Nowadays, you might still find children saying "vous" but it would probably be more to talk to their grandparents not their parents.
I hope it made it clearer for you. :)