Several research groups have attempted to replicate Caspi et al.'s5 findings of increased vulnerability to depression in response to stressful life events for individuals with one or more copies of the ‘s' allele, with most succeeding (see below), even if not all (for example, Surtees et al.23). Going unnoticed in most, even if not all, of this work to be summarized below, however, is the fact that those carrying short alleles (s/s, s/l) did not just function most poorly when exposed to many stressors, but best—showing least problems—when encountering few or none of the stressors. Consider, for example, Taylor et al.'s24 findings (appreciated by the investigators) showing that young adults homozygous for short alleles (s/s) manifested greater depressive symptomatology than individuals with other allelic variants when exposed to early adversity (that is, problematic childrearing history) as well as many recent negative life events, consistent with a diathesis–stress framework, yet the fewest symptoms when they experienced a supportive early environment or recent positive experiences, that is—and importantly—not just the absence of adversity. A similar for-better-and-for-worse pattern of environmental effects emerged in
