Fig. 3: Genetic fine structure.

a, Unsupervised genetic clustering grouped by region. Mean estimated ancestry (K = 8) proportions for all samples in each region are shown in barplots. Map of Greenland with regions coloured (exaggerated inland for visibility) and sample locations indicated with black dots. b, People with birth and sample location in the same region (n = 1,921) visualized on the first two principal components coloured either by birth town region or inferred ancestry proportions. The enlarged areas highlight the ancestry assignment for people between clusters. c, Number of parent–offspring and full sibling relations inferred from genetic data per 100,000 possible relationships between each pair of regions. Grey lines represent sibling relationships, with line width indicating the inferred number of sibling relationships per 100,000 possible relationship pairs. Coloured lines represent parent–offspring relationships, where the colour indicates from which region the parent was sampled and the line width indicates the inferred number of sibling relationships per 100,000 possible relationship pairs. d, Regional differences in AFs for five highly penetrant Arctic-specific recessive variants (coefficient of variation (AF²), SI = 74%, ADCY3 = 251%, PCCB = 164%, TBC1D4 = 42% and ATP8B1 = 149%). e, Expected frequency of homozygous participants for each variant with and without the current fine structure. f, Estimated variant age along with 95% CI of the eight Arctic-specific variants and the variant in FADS2. Coloured percentages are Indigenous allele frequencies of the different regions. Vertical dashed lines are split times between the populations³⁹. Map shows a schematic illustration of the migration routes for the ancestral population that gave rise to the Greenlandic Inuit. P values for directional selection are unadjusted and bold P values indicate significance after FDR(BH), see also Supplementary Table 9.