Accurately modeling the nature of the interaction effect using the G2 term also allows the researcher to use information about the nature of the observed interaction to evaluate the likelihood that the finding represents a real effect. The use of p-value cut-offs is essentially a statistical guide to reduce the likelihood that a finding is a false positive; because genotypes have biological meaning, we suggest that this information should also be used to evaluate the likelihood that a statistically significant effect actually represents a potentially biologically meaningful phenomenon. We suggest that interactions that do not conform to commonly accepted genetic models (additive, dominant, recessive) be viewed with extreme skepticism and only be accepted as evidence of a meaningful gene-environment interaction effect when there is a clear a priori reason to expect that a more complex genetic model is applicable.
