Parental and adolescent smoking: does the association vary with gender and ethnicity?

Aim Determine whether parental smoking is a consistent risk factor for adolescent smoking in a multi-ethnic sample, and whether maternal and paternal effects combine additively or multiplicatively. Methods Annual national cross-sectional surveys (2002-2004 combined) with multiethnic sample of 91,219 Year 10 students from New Zealand who answered a questionnaire on personal and parental smoking. Results Maternal smoking and paternal smoking were associated separately with increased risk of daily adolescent smoking in all ethnic groups except paternal smoking in Asian youth. The relative risk of adolescent daily smoking (adjusted for age and sex) was significantly higher for maternal only smoking compared with paternal only smoking in each ethnic group: Asians 5.50 (95% CI: 3.55-8.52), Europeans 1.38 (1.26-1.52), Pacific Islanders 1.38 (1.10-1.73), and Maori 1.10 (1.00-1.21). The excess maternal effect varied inversely with smoking prevalence. The net effects of maternal and parental smoking are additive among European, Maori, and Pacific Island students, but multiplicative in Asian. Overall, about 40% of adolescent daily smokers could be attributed to parental smoking. Conclusions These results show that parental smoking is a consistent risk factor for adolescent smoking in all ethnic groups. Prevention strategies targeted at parents may help limit the uptake of smoking by adolescents.