Estimating genetic correlations among discontinuous phenotypes: an analysis of criminal convictions and psychiatric-hospital diagnoses in Danish adoptees.

Abstract

A biometrical model-fitting approach was applied to data from a full adoption design to study phenotypic variation and covariation among multiple discontinuous traits. Using statistical methods available for factor analyses of dichotomous-item data, generalized least-squares estimates were obtained for parameters of additive polygenic and environmental influences on criminal convictions and psychiatric-hospital diagnoses in 2532 Danish male adoptees and their family members. The procedure also provided estimates of genetic correlations, environmental correlations, and genotype-environment correlations among the measures while taking into account the effects of selective placement, assortative mating, and cultural transmission from parental phenotypes to off-spring environments. Significant heritable influences were found for property crime and for a composite psychiatric variable pertaining to hospital admissions for alcohol abuse, drug abuse, and personality disorders. Both correlated environmental factors and correlated genetic factors important to the different variables accounted for the observed phenotypic relationship between property crime and these antisocial disorders. No cultural transmission was present for the adoptees' antisocial disorders, although significant paternal cultural transmission was found for property crimes. Patterns of assortative mating differed for the biological versus adoptive parents, and selective placement was found to be negligible.