“They always disfavor me!”: Parental conditional regard undermines teenage sibling relationships through raising competition and perceived disfavoritism

Conditional regard defined as adolescents' perception that parents' affection hinges upon whether they meet parental expectations affects their skills to build stable and sustainable relationships. However, its role in sibling relationships remains unexplored. This study investigates how conditional regard relates to sibling competition, favoritism, and conflict in 201 teenage sibling dyads. Actor‐Partner Interdependence Mediation Models showed that conditional regard was associated with lower sibling relationship quality. Similarities between siblings' reports were low, and siblings' perceptions of parenting mainly predicted their own perceptions of sibling relationships. Competition and feeling disfavored mediated the negative effects of conditional regard on conflict. Feeling favored was predicted by conditional positive regard but did not mediate effects. Our findings highlight the potential of conditional regard to undermine sibling bonds.