Washington, D.C. ? In a study published today, white teens who had watched a lot of R-rated movies or had TV sets in their bedrooms were more than twice as likely to take up smoking compared with other white teens.

The study showed that media exposure had a powerful influence on white kids even when other risk factors, such as peer smoking, were taken into account.

Black teens in the study generally watched more R-rated movies than their white classmates and were more likely to have their own TVs, but their viewing habits didn’t prompt them to smoke. They were more influenced by other factors.

“Why is it that whites are responsive to (media) and blacks aren’t? What’s going on?” said Dr. James Sargent, a professor of pediatrics at Dartmouth Medical School who studies teen smoking but wasn’t involved in the latest research.

Other researchers have documented a broad link between media exposure and teen smoking, but the new study, published in the Archives of Pediatric and Adolescent Medicine, is the first to suggest the effect isn’t universal.