Teens who pick up smoking are significantly influenced by whether older siblings smoke as well as whether their parents currently smoke or did so in the past, according to research from Purdue University.

"It's no surprise that the children of heavy smokers smoked, but what is surprising is that the rate of teens whose parents started smoking later in life or who had quit or reduced their smoking was just as high, if not higher," Mike Vuolo, an assistant professor of sociology who studies youth behavior and substance use, said in a press release.

All told, the researchers determined that the children of later-life smokers were 29 percent more likely to smoke and even more so in the case that their parents started smoking as teenagers but had either quit or reduced their amount

Additionally important, the data showed, was whether or not a sibling smoked..

"Even though these rates are high, young teens are more likely to smoke if an older sibling does, or if they live with a parent who is a heavy smoker," Vuolo pointed out.

For this reason, the researcher argues that anti-smoking prevention for youth should be targeted at the children of parents who smoked at any time in their life or at those whose siblings are engaged in the life-threatening behavior.

The results are based on 214 adults regularly surveyed starting in 1988 at the age of 14 and ending 24 years later. Meanwhile, the 314 children of these adults were between 11 and 19 years old.

"Parents' influence on youth smoking is not new, but the quality of this data has followed the parents for more than 20 years and shows the history of their smoking patterns, specifically length and amount, and how that has affected their children," Vuolo said, pointing out that most previous research is based on one-time surveys completely reliant on retrospective feedback from parents.

Based on an analysis of the participants' responses, the parents were separated into four groups: non-smokers, heavy smokers, light smokers or those who had quit, and late-onset smokers who didn't start smoking until early adulthood.

The data showed that 8 percent of non-smokers' children had smoked in the past year and 25 percent the children of heavy smokers, as defined as at least half a pack a day, reported smoking.

Furthermore, the data showed that children of parents who started smoking as teenagers but quit or reduced their smoking by age 38 smoked at a rate of 23 percent, and the highest percentage of youth smoking, or 29 percent, was by children of parents who started smoking later in life in their 20s.

All of the data were controlled for a wide range of variables, including socioeconomic status and the relationship between the parent and child, according to the researchers who reported surprise at their findings.

"I thought the children of smokers who had reduced their smoking or quit would be significantly lower than the other two groups," Vuolo admitted, adding that, going forward, he hopes to take a look at individual specifics, such as whether or not the parents smoked in front of their children or to what degree the children were exposed to their parents' efforts to quit.

Meanwhile, the researchers determined that an older sibling who smokes is 15 times more likely to occur in the heavy smoking households than the non-smoking households, and a younger sibling is six times more likely to smoke if they have an older sibling who smokes.

This remained the case even if there was a sibling present in the light smoking or early-onset smoking environment, though it was much more likely to happen in the heavy smoking households, the researchers report.

"One aspect to keep in mind is that other research shows that heavy smokers are more likely to have children at younger ages, so they may be overrepresented in this population because they have teenagers at age 38," Vuolo said. "If we did the same analysis 10 years from now, when the non-smokers' children are more likely to be teenagers, what would we see?"