The current investigation tests these ideas using data from a multiwave longitudinal-epidemiologic twin study. This study is large enough for analytic methods to extract the rare, problematic trajectories of alcohol use that are the focus of most research efforts, and long enough to span the developmental arc of normative alcohol use, which increases during adolescence, peaks in early adulthood, and decreases thereafter.20 This study also uses a twin design and includes a wide range of alcohol use correlates, allowing us to assess the genetic and external continuity of extracted alcohol trajectories.
