Heritability estimates and the corresponding confidence and significance levels were calculated using the Sequential Oligogenic Linkage Analysis Routine (SOLAR) statistical package49. SOLAR employs a variance components approach to provide an estimate of additive genetic variance (VA) and the remaining genetic variance (VE) using information from all available family members. The resultant heritability (h2, defined by VA/(VA+VE)) is based on a maximum-likelihood-based variance decomposition approach and does not assume an inheritance model. Because the disorders of interest vary with respect to gender ratios and age, (the sample consisted of individuals ranging in age from 4 to 77), age at interview and gender were controlled for in the heritability analyses. Note that proband status is automatically incorporated into the heritability estimates. Heritability estimates for TS, TS or CMVT, OCD, OCB, OCD or OCB, and ADHD were conducted. To further elucidate the genetic and environmental contributions of each disorder to the phenotype, bivariate analyses were conducted for pairwise combinations of these disorders, and the RhoE and RhoG, corresponding to the environmental and genetic correlations between the traits were calculated. It should be noted
