The present study made use of data from European Americans (EA) and African Americans (AA), broad continental groups statistically inferred from genomic data and the 2 largest continental populations represented in COGA. Continental group assignments were statistically inferred by estimating how similar an individual’s genetic data were to the genomes of 1000 Genomes27 populations from the following: (1) Northern Europeans living in Utah, individuals from Finland, Great Britain, Toscani from Italy, and Iberians from Spain, contributing to a European-like group; and (2) African-Caribbeans in Barbados, Gambians from the Western Division, Esan in Nigeria, Mende in Sierra Leone, Yoruba in Ibadan, Luhya in Webuye, and African ancestry individuals in southwestern United States contributing to an African-like group. Final continental assignment was ascribed on a per family basis as the assignment for most individuals within the family.28 The analytic sample included 1761 EA individuals (51% male; mean age = 16.41 years, SD = 3.29 at first assessment) and 894 AA individuals (52% female; mean age = 16.36 years, SD = 3.31 at first assessment). We note that the concordance between continental group
