Fig. 1

Population structure confounds human genetic studies. A The population that an individual is born into influences their genetics and their environment, which are the two components affecting traits. As a result, genetic associations with human traits are confounded by population structure. B Even when considering a specific human group and controlling for the major axes of genetic variation in a cohort, the allele frequency of some variants can still vary across populations and exhibit clear geographic patterns, a problem known as “residual population structure”