As both height and BMI have repeated measures in the ARIC cohort and BMI also has repeated measures in the HPFS and NHS cohorts, we fitted a repeatability model for these repeated records, assuming that the genetic correlation between repeated observations is unity. We estimated the repeatability of height as ~0.99 in the ARIC study and the repeatabilities of weight and BMI of > 0.93 in all cohorts (Supplementary Table 7). The estimates of hG2 by repeatability model analyses are similar to those using the mean of the repeated measures as in all other analyses (Table 1 and Supplementary Table 7). The ratio of an estimate of hG2 based upon m repeated records to that of a single observation is 1/[(1 − ρ)/m + ρ] with ρ the repeatability27. In this study, ρ > 0.93 and m is small, so that our inference based upon the mean of 3 or 4 observations is very similar to that from a single observation.
