Path Analysis of Family Resemblance and Gene-Environment Interaction

Abstract

The consequences of interaction between genotype and transmissible environment, in path analysis of family resemblance on the assumption of additivity of effects, are examined. For the model considered here, estimates of heritability are found to be biased measures of the proportion of variance due to additive genetic or transmissible environmental factors. Estimates of other parameters are largely unaffected by the interaction. Circumstances in which interaction can be detected are discussed, and a statistical test, based on a comparison of estimates from subdivisions of the data, is proposed. The power of the test is shown to depend critically on the amount of data available for separated relatives.