The intergenerational transmission of tobacco smoking--the role of parents' long-term smoking trajectories.

Youths whose parents smoke tobacco may be at elevated risk of smoking themselves. However, the association between parental long-term smoking history and offspring regular tobacco use is not well known. Using data collected on 1121 youths (12-26 years) participating in the GAZEL Youth study, a French community-based cohort, we tested the association between parental long-term smoking trajectory and offspring regular smoking. Parental smoking trajectory over 11 years (1989-1999) was measured by yearly reports obtained from the parent. Statistical analyses controlled for youth's sex, age, alcohol use and disruptive behavioral problems, parent's sex, as well as family socioeconomic position. Overall, 27% of study youths smoked regularly. Compared to offspring of non-smokers, those of persistent smokers had twofold smoking rates (age and sex-adjusted OR: 1.91, 95% CI: 1.30-2.79, fully-adjusted OR: 1.96, 95% CI: 1.31-2.93). Additionally, persistent parental smoking predicted offspring heavy smoking and early smoking initiation. Overall, maternal smoking was more strongly associated with youths' regular smoking than paternal smoking (fully-adjusted ORs: 3.12, 95% 1.58-6.16 vs. 1.47, 95% 0.87-2.49). These results suggest that efforts to decrease the burden of tobacco smoking among youths may be more efficient if focused on families rather than on individuals.