 The direct method is always preferable, for obvious reasons, but depending on the genetic architecture of the phenotype, is not always possible.Biogeographic ancestry determination methods have been highly developed within the genetics community, as it is a key GWAS quality control step.These approaches typically use genome-wide human genetic clustering and/or principal component analysis to compare new subjects to curated individuals with known ancestry, such as the International HapMap Project or the 1000 Genomes Project.