The Dark Triad In Adult Sibling Dyads

Abstract

This study investigated the degree of similarity / dissimilarity between adult siblings’ Dark Triad scores. 94 sibling pairs participated in the study. The mean age of the older siblings in each pair was 23.3 (19–36). Mean age of the younger siblings: 20.47 (18–30). The methods included a Dark Triad diagnostic questionnaire (the Russian version of the Dirty Dozen) and the Short Portrait Big Five Questionnaire (BF-10). The participants completed each questionnaire twice: first to rate themselves, and then to rate their sibling. The goal of the study was to compare the participants’ perception of themselves (self-ratings), their siblings (ratings of siblings), and their siblings’ perception of themselves (ratings by siblings), and to evaluate the degree of similarity between siblings’ self-ratings and ratings by siblings. We demonstrated that siblings’ self-ratings of Dark Triad traits do not significantly differ from ratings by siblings and of siblings. The intra-pair similarity of Dark Triad traits for self-ratings and ratings by siblings was shown to be low. The structure of the interrelations between traits is similar for older and younger siblings; however, there are some differences depending on who is rating the dark personality traits, the participant or his/her sibling. Ratings by siblings were shown to have higher correlations between Dark Triad traits as well as between the Dark Triad and the Big Five; thus, the coincidence of Dark Triad traits seems to be more pronounced to an external viewer than seen in self-ratings.