Normalised pairwise mean allele sharing within clusters and among sibling clusters. It is common for substantial overlap to be observed between the distributions, but intra-population measures are typically greater than inter-population measures . (a) Within Karitiana, among other sibling clusters from the Americas. This population subdivision defined by structure demonstrated strong population differentiation, even at finer levels of resolution, such that the distributions were completely separated. (b) Within Israel-Negev, among European and other Middle Eastern sibling clusters. Other population divisions defined by structure showed more overlap between the distributions, indicating that although there was strong homogeneity within the intra-cluster population, similar alleles were found in sibling clusters, further indicating that the populations were more closely related. The degree of overlap was quantified to describe the relatedness of the samples being partitioned.