In addition to the interplay between pubertal timing, parent-child relations and adolescent substance use, other influences on the relationships of interest were plausible. First, it is argued that the increased prevalence of obesity in the preadolescent population may play a role in the notion that puberty is starting earlier in Western countries (Fechner, 2003). Adolescent reports of secondary sex characteristics may reflect pubertal development, being overweight or obese or some combined effect of the two. Second, parent alcohol use and smoking behavior can be regarded as a risk factor for adolescent substance use with evidence of genetic effects and modelling effects (Hawkins et al., 1992; Fowler et al., 2007). The effects of Body Mass Index and maternal substance use were therefore considered as part of the analyses.
