Parental Narcissistic Traits and Differential Sibling Treatment: Implications for Marriage and Family Counseling

Parental narcissistic traits and parental differential treatment (PDT) are each associated with adverse family and psychosocial outcomes, yet the empirical overlap between these literatures remains limited. This critical integrative review maps direct and adjacent evidence concerning parental narcissistic traits, favoritism, disfavoritism, scapegoating, and sibling relationships, and evaluates whether unequal sibling positioning is a plausible family process linking parental narcissistic traits with offspring outcomes. Structured searches of Scopus, PubMed, and EBSCOhost resources were supplemented by Google Scholar and citation searching. Evidence was organized by level of inference rather than treated as a single homogeneous literature. Direct studies support scapegoating as one relational pathway and identify psychological control, conditional regard, and attributional processes as plausible mechanisms. The broader PDT literature consistently links relative disfavoritism and larger treatment differences with poorer adjustment and sibling relationship quality, while also demonstrating important child, family, cultural, and reporter effects. The complete causal chain remains untested. For marriage and family counselors, the evidence supports behaviorally specific assessment of sibling comparison, selective blame, conditional approval, coalitions, and perceived fairness while avoiding unsupported diagnostic labeling of parents.