genetic influence on a phenotype, even an endophenotype, from a single cross-sectional snapshot may be somewhat akin to trying to understand the effects of gravity on a falling object while it is frozen in midair. Genes are expressed in particular environments over the course of development, yet our analytic approach ignores this interplay. Considering developmental trajectories may be fruitful. For now, however, the molecular-genetic basis of P3 amplitude remains to be determined.
