Differential contribution of parents and friends to smoking trajectories during adolescence.

The purpose of this study was to assess the relative contribution of friends' and parents' smoking on the age of smoking initiation. A sample of 812 preadolescents, who were part of an accelerated longitudinal design, participated in the study over a 4-year period. Three smoking trajectory groups were first established: an age 11-12 starters group (5.7% of the sample), an age 12-13 starters group (11.1% of the sample), and an age 13-14 starters group (7.9% of the sample). A fourth trajectory group included the children who had not started smoking by age 15 years and who represented the majority of the participants (75.4%). After controlling for parental education, gender, and participants' behavioral and academic maladjustment, a series of logistic regressions revealed that parents' smoking assessed during the same year predicted membership in the age 11-12 starters trajectory group. Both parents' and friends' smoking predicted membership in the age 12-13 starters group. Finally, only friends' smoking predicted membership in the age 13-14 starters group. The results are discussed in light of the controversy about the contribution of parents' and friends' smoking behavior to smoking initiation in adolescents.