et al. (2014a) found a significant GxE effect involving PRS and low parental knowledge and high peer deviance on age 14 alcohol problems, but they used cross-sectional moderation analyses on a twin sample (FinnTwin12). The failure to replicate previous findings does not necessarily indicate the absence of a GxE effect, but reflects the well-known challenges of uncovering small GxE effects within a limited study sample size for complex phenotypes (see Manuck and McCaffery, 2014 for relevant review on this topic). Studies should continue to prioritize analytic rigor (e.g., longitudinal modeling, multiple measures of the environment) and cutting-edge genotyping assays to more precisely characterize the extent to which genes and environments interact as they relate to complex phenotypes.
