The GCTA heritability of Wave II, Wave III and Wave IV BMI based upon a sample of whiterespondents was estimated to be 0.82 (SE=0.081), 0.71 (SE=0.091), and0.67 (SE=0.084) respectively. Using a bivariate approach, the GCTA genetic correlation between Waves II/III, Waves II/IV and Waves III/IV were estimated to be 0.95 (SE=0.031), 0.85 (SE=0.042) and 0.99 (SE=0.033) respectively. The degree of relationship among the 1,886 individuals used in the genome-wide association analysis varies. In all, there are 614 individuals who are not 1st degree relatives (siblings) of others in the sample (N=614), 609 sibling pairs (N=1,218 individuals) and 18 sibling trios (N=54). Tables 2 and 3 provide the characteristics of the sample used for the genome-wide analysis. As noted previously and seen in table 2, approximately half of the sample self-identifies as White, 36% Black, 11% Hispanic, 4% Asian and less than 1% as Native American. Table 3 shows the frequency of males (48%) and females (52%) as well as the mean age and BMI of the sample at each wave of collection. Consistent with other studies, the mean (and standard deviation) of BMI increases throughout young adulthood.
