As noted by Moffitt et al. (2005), there has long been a belief by some in behavior genetics that “GXEs are so infrequent that they can safely be ignored” (p. 473) and this attitude has only recently changed. In order to facilitate further work on human GXE interactions, Moffitt et al. recommend a seven-step strategy that goes beyond brute force scanning and, logically, should help identify the most promising candidate interactions. These steps can be summarized as: (1) “consulting” (i.e., taking leads from) the quantitative behavior-genetic literature (e.g., twin studies), (2) “identifying a candidate environmental pathogen for the disorder in question,” (3) “optimizing environmental risk measurement,” (4) “identifying candidate susceptibility genes,” (5) “testing for an interaction,” (6) “evaluating the specificity of the interaction”, and (7) “replication and meta-analysis.” To this list should be added (5a) evaluating the dependence of the observed interaction on choice of measurement scale (e.g. Jinks and Fulker, 1970) or, particularly in the case of binary phenotypes, the appropriateness of implicit modeling assumptions (e.g. Eaves, 2006; Heath et al., 2008). There is a more restrictive viewpoint that,
