different population groups and perhaps complex relationships reflecting different population origins that includes migration, admixture, and isolation. In addition, the much larger SNP set, 300K compared to maximum of 10K SNPs in previous studies, is also likely to have exposed aspects of substructure not evident in other studies. For PC's >1, comparison of sets of <11K SNPs had much lower correlations with the full 300K SNP set than those random sets with >40K SNPs (Table S3).
