As much as everyone is probably going to disagree with me on this one, I would respect your parent's request. I mean, they are putting a roof over your head, putting food on your plate, paying the bills, they're fucking taking care of you man. If you really want to smoke, then just wait until you've graduated from high school and move out. Then you can do whatever the fuck you want. This is coming from the mouth of experience, the last thing you want is for your parent's not to be there for you when you need them the most. And if you disrespect them by smoking behind their backs, they might just turn theirs on you.