I briefly review three highly-cited examples from the G×E literature where investigators improperly attempted to control for covariates in their regression models. The purpose is not to draw attention to these studies per se, nor to suggest that they are particularly egregious examples of this practice; as shown below, no G×E study reviewed here properly controlled for covariates. Rather, the purpose is to better illustrate the problem with examples representative of the field, and to allow the reader to gauge the plausibility (or implausibility) of alternative explanations that could have been tested had investigators properly controlled for covariates.
