Mike Vuolo of Purdue University in Indiana and Jeremy Staff of Pennsylvania State University analyzed data from 214 parents and 314 children ages 11 and older. Eight percent of the children of non-smoking parents smoked in the last year.
Of children of smokers, 23 percent to 29 percent had smoked in the past year. Rates varied according to how consistently the parents smoked, but even children of "light" smokers who reduced or quit later in adulthood had a higher risk of smoking.
The study, published online ahead of the September print edition of the journal Pediatrics, found parental smoking at any age, even before the child was born, increased the odds their children would smoke.
Children who had an older sibling who smoked were more than six times more likely to smoke than children who do not have a sibling who smoked.
An older smoking sibling was 15 times more likely to be present in a household with a heavy-smoking parent compared to non-smoking parents, the study said.