Such contextually dependent variation in genetic risk is sometimes referred to as genotype-environment interaction (GxE). It is important to note that the term genotype-environment interaction is also used to refer to situations in which the genotype confers susceptibility to an environmental risk (or vice versa). This type of GxE affects the mean scores of a trait, as demonstrated using adoption studies (Cadoret et al., 1995) and molecular techniques (Caspi et al., 2003). In contrast, the interactions discussed in the current paper refer to moderation of the variance and variance components of the traits. As a result, any conclusions drawn from one type of study are not directly applicable to the other. Furthermore, the term “E” as used here may not strictly refer to an environmental factor. Instead, it refers to anything that moderates the magnitude of variance components. This could be a shared environment effect, a non-shared environment effect, or even another phenotype. To avoid confusion with the GxE described above, and to incorporate the concept of a moderator variable that may or may not be truly environmental, we will
