Notably, the shared environment component (C) did not have any contribution to the etiology of OCS in this study. Taylor, 2011 [1] have also previously reported that the shared environment has a weak contribution to the OCS phenotypic variance. This finding is particularly relevant to the clinical field because it suggests that family environment (e.g., learning) is unlikely to have a major role in the etiology of the disorder. Instead, future studies should focus on the impact of specific environmental factors that are not shared between siblings or twins. Discordant sibling and twin designs are particularly suited to move the field forward because they effectively adjust for shared genetic factors and unmeasured confounders [3]. Using such designs, researchers have recently confirmed a dose-response relationship between perinatal complications and risk of OCD in the offspring [74].
