A MODEL SYSTEM FOR ANALYSIS OF FAMILY RESEMBLANCE IN EXTENDED KINSHIPS OF TWINS

The ''Virginia 30,000'' comprise 29,698 subjects from the extended kin ships of 5670 twin pairs. Over 80 unique correlations between relative s can be derived from these kinships, comprised of monozygotic (MZ) an d dizygotic (DZ) twins and their spouses, parents, siblings, and child ren. This paper describes the first application of a fairly general mo del for family resemblance to data from the Virginia 30,000. The model assesses the contributions of additive and dominant genetic effects i n the presence of vertical cultural inheritance, phenotypic assortativ e mating, shared twin and sibling environments, and within-family envi ronment. The genetic and environmental effects can be dependent on sex . Assortment and cultural inheritance may be based either on the pheno type as measured or on a latent trait of which the measured phenotype is an unreliable index. The model was applied to church attendance dat a from this study. The results show that the contributions of genes, v ertical cultural inheritance, and genotype-environment covariance are all important, but their contributions are significantly heterogeneous over sexes. Phenotypic assortative mating has a major impact on famil y resemblance in church attendance.