Heritability estimates from SNP data using only ‘unrelated' individuals were substantially lower than estimates reported by twin and family studies (analysis 1 in Supplementary Information Table S3). Heritability estimates from both SNP and pedigree data using all individuals, however, (analyses 2 and 3 in Supplementary Information Table S3), confirmed a moderate heritability for both neuroticism and extraversion from twin and family studies (∼42% from SNP analyses and ∼45% from pedigree analyses). Note that estimates of variance from analyses including close relatives are increased by the effects of all causal variants (rather than only the effects of causal variants in sufficient LD with the genotyped SNPs included in the analyses), but may also be inflated by confounding of closely related individuals and common-environmental factors and nonadditive genetic effects.
