to be swinging back the other direction. However, a recent review by Caspi and colleagues entitled “Genetic Sensitivity to the Environment: The Case of the Serotonin Transporter Gene and Its Implications for Studying Complex Diseases and Traits” highlighted the fact that evidence for involvement of 5-HTT in stress sensitivity comes from at least four different types of studies, including observational studies in humans, experimental neuroscience studies, studies in nonhuman primates, and studies of 5-HTT mutations in rodents (Caspi et al. 2010). Further, the authors made the distinction between different cultures of evaluating gene-environment interactions: a purely statistical (theory-free) approach that relies wholly on meta-analysis (e.g., such as that taken by Risch et al. 2009) versus a construct-validity (theory-guided) approach that looks for a nomological network of convergent evidence, such as the approach that they took.
