Attempts at replication of the original findings by Caspi and colleagues have been mixed, due at least in part to variation in measures of both the predictive variable (childhood maltreatment) and the outcome variable (antisocial or aggressive behavior). In most cases, researchers have focused on extreme levels of both the environmental risk and the behavioral outcome, and have limited their outcome assessment to adults. Another possible explanation for these inconsistencies is the presence of an as-yet-unidentified third variable influencing outcome, which could be environmental or genomic in nature.
