How do you know your child is growing up?

How do you as a parent now when your child is growing up. For me it is when you as a parent have drawn a line in the sand (made a decision) and your child tries to cross it. This is when I now that they are growing up to start to make decisions for themselves. Too many parents want to control their children and too many children want to be controlled (told what to do). I am proud to see when my children want to cross the line that we have put up for them. It is great to see them grow.