The more time a child is around a parent who smokes, the greater the chance the child will become a regular smoker, researchers said.

The researchers looked at smoking patterns: timing, duration and nicotine dependence. With each additional year of exposure to a parent smoking, the child was more likely to become a smoker, they said.

This finding, the researchers said, provides more information than the usual parameter of whether or not a parent smoked.

A study published this week in the journal Pediatrics by researchers at Georgetown Lombardi Comprehensive  Cancer Center looked at 406 adolescents and one of their parents, with followups in one and five years. The participants were part of the New England Family Study, which was designed to shed light on intergenerational smoking patterns.

Four adolescent patterns emerged: those who started smoking early and smoke regularly, 6%; those who tried smoking early, 23%; those who tried it later, 41%; and nonsmokers, 30%. Adolescents of parents who were “nicotine-dependent” at the start of the study were more likely to be in the category of those who started early and smoke regularly.

The longer the parents smoke, the researchers said, the greater “the likelihood [the adolescents] will be in a heavy smoking trajectory.”

What’s needed, the researchers said, are ways to help parents quit smoking early in a child’s life.

One limitation of the study is that one parent was interviewed in the family, leaving no data for assessing any differences between a mother or a father, or both, smoking.