A model system for analysis of family resemblance in extended kinships of twins

Abstract

The "Virginia 30,000" comprise 29,698 subjects from the extended kinships of 5670 twin pairs. Over 80 unique correlations between relatives can be derived from these kinships, comprised of monozygotic (MZ) and dizygotic (DZ) twins and their spouses, parents, siblings, and children. This paper describes the first application of a faMy general model for family resemblance to data from the Virginia 30,000. The model assesses the contributions of additive and dominant genetic effects in the presence of vertical cuItural inheritance, phenotypic assortative mating, shared twin and sibling environments, and within-family environment. The genetic and environmental effects can be dependent on sex. Assortment and cultural inheritance may be based either on the phenotype as measured or on a latent trait of which the measured phenotype is an unreliable index. The model was applied to church attendance data from this study. The results show that the contributions of genes, vertical 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 family resemblance in church attendance.

A twin-family study of self-report symptoms of panic-phobia and somatization

“…Readers interested in the full details of the statistical analyses performed in this paper should consult Truett et al (1994). We provide an abbreviated summary here.…”

Classical twin studies and beyond

“…TABLE 1 summarizes the possibilities for research that go beyond the classical twin design. Extending the MZ-DZ design to include the testing of parents, siblings, spouses and offspring of both MZ and DZ twins, offers the opportunity to assess the presence of cultural transmission, genotype × environment covariance, non-random mating, and social interactions within and between generations 24 . Simpler versions of the fuller, extended twin studies -such as a study of youngadult twins, their middle-aged parents and a second group of middle-aged twins (that is, twins of the same age as the parents of the first group of pairs of twins) -makes it possible to assess the effect of age differences on heritability and to assess differential gene expression as a function of age.…”

Genetics and the Social Science Explanation of Individual Outcomes

“…Neuroticism (Loehlin 1992) Smoking (Li 2003) Church attendance (Truett et al 1994) Educational attainment (Behrman and Taubman 1989) Obesity (Mease, Neale, and Eaves 1997) Social skills (Scourfield et al 1999) Cognitive ability (Daniels, Devlin, and Roeder 1997) Electoral participation (Fowler, Baker, and Dawes 2008) Occupational attainment (Behrman et al 1980) College plans (Nielsen 2006) Extraversion (Loehlin 1992) Openness to experience (Loehlin 1992) THE PHENOTYPIC BOTTLENECK Knowledge that something has a causal effect makes it easy to confuse the task of explaining Why do genes affect y? with the task of explaining y; that is, of providing a logically continuous account of why y differs for different people.…”