As a child enters into adolescence, social behaviour moves away from interactions with the parents to interactions with peers.
Suddenly being accepted and fitting in becomes important and social behaviour is a key part in this. For a typically developing teen, they have to make choices about what social behaviours they engage in and which they don’t. Consider a group of teens who have begun to smoke or drink on the school property and they are asked (mand) if they want to smoke too? If the teen says yes, he is reinforced by acceptance from his peers, but if he says no, he separates himself from this particular group of peers.
Our social interactions are influenced by how we are reinforced for things we do, so you can see that it is very important to ensure our children are accessing reinforcement for desirable behaviours that will impact their future positively.