The supervised ADMIXTURE ancestry analysis by Thornton et al. [2013] revealed that most of the GAW18 sample individuals have European and Native American derived ancestry, but with quite variable ancestry proportions. Proportional European ancestry ranged from 0% to 96%, with a 45% mean and a 14% standard deviation. Proportional Native American ancestry ranged from 0% to 84%, with a 50% mean and a 14% standard deviation. These proportions are consistent with previous reports for Mexican American samples [Thornton et al., 2012; Manichaikul et al. 2012]. The African and East Asian ancestry proportions in GAW18 were modest, with corresponding mean proportions of 4% and 1%, respectively. Figure 1 shows a plot of the clustering results from an unsupervised ADMIXTURE analysis of GAW 18, HapMap CEU, HapMap YRI, and HGDP Native American samples, assuming that there are three ancestral populations. The vast majority of GAW18 individuals fall between the HapMap CEU cluster and the HGDP Native American cluster but with proportional ancestry being quite variable. The individual ancestry results from the unsupervised analysis with reference population samples included are complementary to those
