YOU are your own man. Your as good as an adult now. Your not some silly kid. You've done your own research and you enjoy what you do. You have the RIGHT to do what you do.

Dont listen to her. Do everything like normal, and keep smoking. If she catches you again, tell her. She's your mother, yes, but that doesnt mean she can tell you what you can and cant do, especially when she doesnt know what shes talking about, and even more so when she wont even accept scientifically proven fact.

Dont give up for her, only give up if YOU want to.