A strength of this investigation, and the others in this special issue, is that our sample comprises families, which allowed us to estimate the heritability of EEG parameters by means of biometric models and test for specific genetic variants in the same sample. Heritability estimates were substantial, and SNP heritability estimates indicated that as much as half the heritable variance in EEG endophenotypes is likely accounted for by the common variants on our genotyping array. However, we identified few specific variants, whether SNPs or genes. If EEG parameters are in fact a result of the additive effects of many genes each with very small influence, understanding the genetics of such traits is likely to continue to present interesting challenges, both methodologically and conceptually.
