Well it really isn't your fault if that helps at all.
Well when I was 15 not to long ago if their was somthing I wanted to do and my parents said no I would do it anyway. When I was that age at least, "no" just ment don't get caught. Heck 4 years later and nothing has changed. Luckly he is still young and probably hasn't been doing it for long. It is probably better he was caught now insted of in a few years. Back in highschool pot was a group and friend thing, chances are he was smoking with other people.
Good luck I hope everything works out!
