Yep, they eventually want to do something that you think they shouldn't, so you say no. When they're little, they accept it but when they get older, they get pissed after hearing "no" so many times and make an outburst about how unfair the parents position is. That's the time for the discussion. I always remind them that they're free to make their own decisions, but that I have a lot of experience and they should consider me as a resource for input when making decisions. I sometimes reciprocate by asking their opinions of things.