Friends have a strong influence over whether teenagers move from experimenting with cigarettes to becoming full-fledged smokers - but so do parents, a new study finds.

The study, which followed 270 teenagers who had become occasional smokers before high school, found that 58 percent made it a daily habit by 12th grade.

But the likelihood of that happening depended partly on friends and parents, according to a study published in the journal Pediatrics.

When friends or parents smoked, teens were more likely to become daily smokers. On the other hand, they were less likely to become habitual smokers when their parents had a “positive family management” style - monitoring their comings and goings, doling out reasonable punishments for rule-breaking and rewarding good behavior.

Overall, teens whose parents kept tabs on them and were non-smokers themselves had a 31 percent chance of becoming daily smokers. The odds were 71 percent among teenagers with parents who smoked and were more lax in managing their kids’ behavior.

“We found that parents play an important role in preventing teens’ smoking escalation from experimental to daily smoking,” lead researcher Dr. Min Jung Kim, a research associate at the University of Washington in Seattle, told Reuters Health in an email.

There appear to be several ways parents can make a difference, according to Kim.

First, if they smoke, they should quit, she advised. In addition, parents should aim for “effective supervision and appropriate punishment or rewards for children’s behavior.”

That, according to Kim, includes knowing your children’s friends and laying out rules for their behavior, including smoking.

“Parents need to make sure they establish clear guidelines in their families about smoking and discuss these with school-aged children,” Kim said.

Previous studies have been consistent in finding that friends’ smoking habits are the best predictor of whether a teenager will become a regular smoker. In contrast, some researchers have argued that parents have relatively little influence once their kids hit adolescence.

The current findings would suggest otherwise, according to the researchers. Instead, Kim noted, parents would seem to have an important role in counteracting peer pressure.

SOURCE: Pediatrics, September 2009.