It is important to note that change in the overall heritability across environmental contexts does not necessarily dictate that any one specific susceptibility gene will operate in a parallel manner. However, a change in heritability (which reflects the aggregate influence of all the individual genes) suggests that at least a good portion of the involved genes (assuming many genes of approximately equal and small effect) must be operating in that manner for a difference in heritability by environment to be detected. Thus, it represents a good piece of evidence from which to build hypotheses about gene by environment interaction effects that may be associated with specific candidate genes.
