English: Examination of brain imaging and single-nucleotide polymorphisms (SNPs) data from ~2,700 individuals. Substantial proportion of variation in cortical surface area is explained by additive effects of SNPs dispersed throughout the genome, with a larger heritable effect for visual and auditory sensory and insular cortices (h²~0.45). (a) Estimates of variance explained by all autosomal SNPs for each cortical region (SNP heritability) from genetic relationships <0.025 (GRM<0.025). Error bars represent the s.e. of the estimates. Estimates were tested for significantly different from zero by likelihood ratio test comparing the full and reduced models. *P<0.05, **P<0.004 (Bonferroni correction threshold). (b) Genetic clustering map shows the anatomical location of the cortical phenotypes16. (c) SNP heritability estimates (blue bars) are overlaid on twin heritability estimates (grey bars). Shared environmental variances are small and not significant for all phenotypes. A: additive genetic variance; C: shared environmental variance; E: unique environmental variance.