The response inhibition construct under study here was previously validated through factor analytic work by Miyake, Friedman, et al. (2000), who demonstrated that three common executive functions (response inhibition, working memory updating, and task-set switching) were correlated but separable at the level of latent variables (see also Friedman et al., 2006). A replication and extension of this work demonstrated that these three executive functions share a highly heritable common factor that can be distinguished from that of IQ or speed (Friedman et al., 2008). In light of the finding that behavioral disinhibition itself is also highly heritable, the third question we asked in this study is as follows: Can the relationship between behavioral disinhibition and response inhibition be explained by shared genetic factors and, if so, to what extent?
