ABSTRACT
This chapter focuses on a specific category of statistical interaction, genotype-environment interaction (GE). Although this is a very restricted view of interaction, it has the merit of leading directly to empirical research that attempts to identify statistical interactions between genetic and environmental effects, thus going beyond the traditional approach of behavioral genetics that stops with the estimation of genetic and environmental main effects. Discussions of genotype-environment interaction have often contused the population concept with that of individual development; the latter view has been called interactionism. Usually interactionism refers to the truism that behavior cannot occur unless there is both an organism and an environment as indicated in the frequently cited quotation, "the organism is a product of its genes and its past environment". In this sense, interactionism is the view that environmental and genetic threads are so tightly interwoven that they are indistinguishable.
