I was caught smoking when I was 13 and was physically punished and grounded by my smoking parents. The only thing it taught me was contempt. It sure as hell didn't make me quit.
I understand winnie's point about it being legal at a certain age just like drinking, and I understood it when I was 13. I also understood my parents were addicted to nicotine as is anyone who has that habit. All my 13 year old mind knew was that I was being punished for their addiction.
They were hypocrites and nothing changes that. No matter the age, being punished for smoking by two smokers made as much sense as me drinking a beer tonight and getting reprimanded by a drunk.
I've quit smoking five times in my life and two of those times were during pregnancy and breastfeeding afterward. Thankfully my kids didn't smoke as minors but I was prepared if they did. Since I was smoking again, my boundaries would've been no smoking around me or my home. Violating the boundaries, though, would have lead to consequences.