Thus, in addition to meeting the Belsky et al.13 criteria for establishing differential susceptibility summarized earlier, which informed the interpretation of study findings considered herein, several other research desiderata are called for. First, studies should measure not just the presence of adversity and its absence, but environmental support, like Taylor et al.24 did in assessing positive life events and Bakermans-Kranenburg and van IJzendoorn41 did in measuring sensitive parenting. Second and relatedly, human functioning should be measured along a continuum ranging from dysfunction to competence, not just from dysfunction to its absence or just from competence to its absence, to avoid the masking of differential susceptibility by ceiling or floor effects; should this not prove possible for some reason, separate measurements of negative and positive functioning should be obtained and examined vis-à-vis G × E. In addition, once a G × E interaction has been discerned, follow-up analysis should determine whether significant differences in the functioning of individuals hypothesized to be more and less susceptible to environmental influences are obtained when the environmental circumstances are adverse as well as when they
