nine time points between the ages of 12 and 22, growth mixture modeling was used to identify three discrete trajectories of general externalizing behavior: 57.8% of the sample showed modest initial levels of externalizing problems that declined over time, roughly one-third (33.4%) of the sample displayed more moderate levels of externalizing problems that also declined with age, and 8.8% of the sample was characterized by higher initial levels of externalizing behavior that peaked during the late teenage years, but persisted into adulthood. Generally speaking, individuals displaying the most modest initial levels of externalizing problems were significantly less likely to carry additional copies of CHRM2 risk variants than were those with either stable high or decreasing moderate levels of externalizing behavior throughout adolescence and into early adulthood. As such, our findings build on earlier work by confirming links between CHRM2 and general externalizing behavior in a non-clinical population, and by broadening the nature of this association to incorporate differentiation between more developmentally relevant measures (trajectories) of externalizing behavior. Moreover, the GMM presented here extends that which was previously reported by our group in relation to GABRA2 and parental monitoring (Dick et al., 2009). Findings from the initial study indicated that a
