Some data in a new report by the Surgeon General on the risks and frequency of teen smoking cigarettes:
http://www.kaiserhealthnews.org/Daily-Reports/2012/March/08/teenagers-and-smoking.aspx
and some teens may have a neurological predisposition to addiction:
http://twocircles.net/2012apr30/brain_networks_explain_why_some_teenagers_smoke.html