The Role of Personality in Perceptions of the Fairness of Parenting and Sibling Relationship Quality

This study examined whether fairness perceptions statistically mediated the curvilinear associations between perceived parental differential affection and control and sibling relationship quality and whether Big Five personality traits moderated these pathways. Participants were 555 undergraduates (54% women; ages 18–25, M = 20.66, SD = 1.66) who reported on parental differential treatment, fairness perceptions, personality, and sibling relationship quality. Fairness perceptions mediated the associations between both forms of differential treatment and sibling relationship quality, with relative equality generally associated with better relationships. Conscientiousness moderated the linear association between differential affection and fairness, whereas Openness moderated the linear association between differential control and fairness, their indices of moderated mediation were not significant. In contrast, the curvilinear indirect association involving differential affection varied by Openness, Extroversion, and Agreeableness. Lower Openness and higher Extroversion were associated with greater sensitivity, when the sibling received more affection, whereas higher Agreeableness was associated with sensitivity to inequality in either direction. These findings suggest that personality shapes the strength and symmetry of fairness-related responses to unequal parental affection without fundamentally changing the broader pattern favoring relative equality.