In testing these questions, it is important to acknowledge that a limitation of the candidate gene literature is the lack of replicability across studies [70]. This lack of replicability raises concerns that results from candidate gene studies are false positives, especially those found using small sample sizes such as in the current study (N = 292). We reduced the likelihood that our results were false-positive findings in several ways. First, we minimized the number of statistical tests performed by using only one SNP within one gene based on theoretically and biologically plausible reasoning. Second, this particular SNP and gene have shown associations with impulsive personality traits and externalizing problems in numerous other studies and in one meta-analysis [8–25]. In this way, our study serves as a replication of these prior studies. If our findings replicate those from previous studies, this will increase confidence that our results are not due to chance. Third, we included covariates to ensure that associations among GABRA2, disinhibition, and externalizing problems were not due to associations with other related (i.e., third) variables. Finally, we corrected for multiple testing to further reduce the likelihood of spurious findings.
