estimated variances compared to the 22 simultaneously estimated variances would provide evidence of stratification. The total variance explained was 26% for chromosomes fitted separately compared to a total of 23% when fitted together, demonstrating little evidence of population stratification (Figure 1a). The estimates of variance explained by each chromosome are linearly related with the length of the chromosome (correlation = 0.89, p = 2.6 × 10−8), consistent with a highly polygenic model and remarkably similar to results for human height12.
