The total additive heritability for each of the five covariate-adjusted clinical phenotypes was determined through analysis of the twin and adoption data using standard biometric approaches (Neale, Boker, Xie, & Maes, 1999). We also used genome-wide complex trait analysis (GCTA) to estimate the percent of phenotypic variance accounted for by additive effects of all the genotyped SNPs(Yang, Lee, Goddard, & Visscher, 2011). Following standard guidelines, only individuals with coefficients of relationship < .025 were included in the GCTA. Biometric analysis and GCTA was undertaken on the residuals of each of the five clinical phenotypes on the full covariate set described above.
