All people must be able to do whatever they want in principle since I put great emphasis on freedom as long as public interest doesn't suffer. Ironically, I also believe that parents should give their children proper advices = advice regarding to the issues that can't be overlooked such as drugs like cocaine and morphine and virulent diseases. Young people are prone to spontaneous behaviors, some of which are irreversible. Indeed, it has been known to be tricky to have someone freed from drug addiction, for instance. They might regret what they have done in early days without having known how grave situation it could have resulted in. Had they known the common consequences, they could have made a better decision. To this end, parents are obliged to guide their children so they can truly live in a way they really wanted. If they still choose precarious things, so be it.