Abstract
The papers in this special issue have in common an interest in developmental variations in the heritability of substance use, abuse, and problems. A number of the studies are longitudinal, and even those that are cross-sectional are analytically focused on whether heritability, shared, and nonshared environmentality effects are constant or change over the period from onset of use to the time when problem use is more constant. This commentary provides an overview of the work from a developmental psychopathology perspective. Findings are linked to the existing longitudinal/developmental literature on the epigenesis of substance use disorders and similarities and contradictions are noted. Suggestions for next step work, involving the need for increased differentiation of the substance abuse phenotypes, the utilization of phenotypic measures that delineate heterogeneity of course, and more precise definition of the specific environmental variations that underlie shared and nonshared environmental liability, are provided.