absence of alcohol consumption. Hence, both Figures 1b and 1c posit increases in the overall variability in P300 amplitude with increasing alcohol consumption. Figure 1b illustrates what we might expect if alcohol consumption increases the genetic variability in P300 amplitude because the environmental adversity that derives from the effects of alcohol on the adolescent brain alters genetic expression. This figure is consistent with a diathesis-stress model wherein the inherited liability for alcohol misuse indexed by P3AR is enhanced with exposure to the adverse environment. Figure 1c also indicates that variability in P300 amplitude increases with adverse environmental exposure, but here the effect is due entirely to the nonshared environment (e.g., by alcohol poisoning brain cells involved in P300 generation).
