The identification of the ancestry groups using non-hierarchical clustering algorithms or for that matter PCA, is enhanced by the inclusion of representatives of the parental population groups. In the analyses performed in the current studies there were representatives of the different continental groups. The inclusion of these groups is particularly important when admixed populations are being examined. The inclusion of these groups, even without specifying population membership, allows more accurate cluster separation. In general, and specifically for the studies reported herein, we did not specify population membership, an available option in the STRUCTURE program. [Similar results are obtained using this option but with larger confidence intervals (data not shown)]. To facilitate the appropriate application of the AIMs described in this study, the genotypes of continental populations groups are provided as a resource to the scientific community (Supplementary Table S6).
