In the present study, the sample was comprised exclusively of Caucasians and we found consistent support for the main effect of sex and trauma exposure on the risk for alcoholism. These variables were significant covariates in all models and without these statistical controls the G × E effects were obscured. Rates of exposure to traumatic stress were also quite high in this sample with 50.51% of cases and 28.65% of controls endorsing exposure to either sexual or physical trauma. An even higher percentage of the sample endorsed exposure to non-physical or non-sexual traumas (64.37%) suggesting that the degree of traumatic exposure may impact the ability to detect meaningful G × E effects. Additional studies that can more effectively delineate the nature and intensity of traumatic stress (or childhood trauma) are required to effectively capture genetic effects on clinical outcomes. Failure to properly operationalize the stress or trauma experienced may lead to mixed findings in the G × E literature of psychiatric disorders (Caspi et al., 2010).
