Fig. 3.

Intra-class circular correlations for polar angle (A), and Spearman correlations for eccentricity (B), and pRF size (C). MZ twin pair correlations are plotted against those for DZ twins. The dashed line is the identity line. Error bars denote 95% confidence intervals derived through 10,000 bootstrap samples. The black symbols on the x- and y-axes denote the average correlation between unrelated participants across the whole sample. D. Correlation difference estimates for population receptive field parameters in each visual region. Data are shown for polar angle, eccentricity, and pRF size parameters, as derived from pRF analysis. Filled circles indicate the group means. The violin plot shows the bootstrap distribution for each pRF property and visual region, and the error bars denote 95% confidence intervals. Asterisks indicate significant differences at p < 0.05, after Bonferroni correction for multiple comparisons. E. Multidimensional heritability estimates for the same pRF parameters. Symbols indicate the observed heritability, error bars denote the 95% confidence interval from bootstrapping.