One study breaks that down by good guys and bad guys.
Susanne Tanski of Dartmouth Hitchcock Medical Center looked at survey data on more than 6,500 teens.
Tanski says teens who saw bad guys smoking were more likely to start than teens who saw good guys smoking. But she says there were more good guys, which heightened their effect, raising the proportion of those teens to start smoking.
She says: "We really do need to make sure that parents are aware that these observations really do impact on their kids behaviour, and talk about that so that it doesn’t look so glamorous – or villainous, if that’s what’s interesting the child."
The study in the journal Pediatrics was supported by the National Institutes of Health.
(Source: US Department of Health and Human Services: Pediatrics: July 2009)