Genetic influences on P3 have been assessed in many twin studies that consistently showed significant genetic influences, although there was some variability in heritability estimates despite differences with respect to subject samples and ERP tasks across studies. Many of these studies are summarized in an excellent review and meta-analysis of twin studies of oddball-P3 conducted by van Beijsterveldt et al. (2002). In this analysis, the “AE” model including additive genetic (A) and non-shared environmental (E) factors was the best fitting one for both P3 amplitude and latency, and the overall estimate for heritability was 60% for P300 amplitude and 51% for P3 latency, with the remaining variance explained by unique environmental factors. It should be noted, however, that a study using repeated longitudinal assessments of P3 estimated heritability of the “stable” variance at 90% (Carlson and Iacono, 2006), suggesting that heritability of a single measurement is substantially attenuated by measurement error.
