that the best fitting ACE model indicated that the non-shared environment could be dropped from the model without sacrificing model fit, leaving genes accounting for about 60% of the variability in P300 amplitude and the non-shared environment accounting for the remaining 40%. Heritability, while a necessary requirement for an endophenotype, characterizes the influence of genes across all environments experienced by the participants. Thus, an important step in establishing the clinical utility of P3AR as an endophenotype is demonstrating that the heritability of P3AR does not vary systematically with environmental adversity that could both promote alcoholism and disrupt P300 amplitude development.
