The chromosomes of an individual with admixed ancestry represent a mosaic of chromosomal blocks from the ancestral populations, and the overall genetic ancestry, or global ancestry of an individual, has previously been defined as the relative proportion of ancestral blocks from each contributing population across the chromosomes [Tang et al., 2005]. Thornton et al. [2013] estimated proportional European, African, Native American, and East Asian ancestry for all genotyped individuals from the 20 pedigrees in GAW18 using the ADMIXTURE software program [Alexander et al., 2009]. The estimation of proportional ancestry was supervised, based on SNP data for odd numbered autosomes, where the CEU and YRI samples of release 3, phase III of the International Haplotype Map Project (HapMap) [International Hapmap 3 Consortium, 2010] were used as surrogates for European and African ancestry, and surrogates for Native American and East Asian ancestry were obtained from the Human Genome Diversity Project (HGDP) [Li et al., 2008]. The Native American ancestry proxies from HGDP were the combined samples from the Americas (Surui, Maya, Karitiana, Pima, and Colombian samples). Chen et al. [2013] performed a
