What I've told my step kids and my own daughter is that no one, I repeat, no one, can tell if they will have an alcohol or nicotine addiction ahead of time. The younger you start either, the longer you will drink and/or smoke. I, despite the 65 year nicotine addiction that killed my 79 year-old Father in a very gruesome manner, started up pipes gain this January after a 32 year or so layoff. I figured I've waited this long, so what the f--k, one or two pipes a day is worth the risk, and damn, the aroma of that Balkan Sasieni with a bit of rye whiskey (a half sheet of whiskey-wet paper towel folded and buried in the middle of a pound in a jar sure has made it worth it so far. So much for the "gruesome death" as a deterrent.
I believe that moderation in all things sounds good, except for sex, of course. No one goes in search of a "moderately" good time in bed. Of course you'll settle for it, but you're (hopefully) not seeking it.