According to the Family Systems theory, family members are part of an interdependent network in which individuals and relationships affect other family members or other relationships. This study...Show moreAccording to the Family Systems theory, family members are part of an interdependent network in which individuals and relationships affect other family members or other relationships. This study examines the association between the quality of the parent-child relationship and the quality of the sibling relationship and investigates if perceptions of differential parenting mediate the association between within-family differences in parent-child relationship quality and sibling relationship quality. Sibling relationship quality, parent-child relationship quality and the magnitude of perceived differential parenting were assessed in a sample of 26 Dutch sibling pairs aged between 8 and 15 years old and their biological and/or legal parent, using the Parent-Child Interaction Questionnaire - Revised, the Sibling Relationship Questionnaire - Short version and the Sibling Inventory of Differential Experience. The results showed that older siblings and younger siblings reported the same relationship qualities and the same magnitude of differential parenting. In line with the Family Systems theory, the association between the quality of the parent-child relationship and the quality of the sibling relationship was significant for older siblings. Moreover, there was no mediating effect of differential parenting, but differences in parent-child relationship quality and sibling relationship quality were positively related. For younger siblings both associations were not significant. However, the associations between relationships of the older siblings were not significantly different from the associations for the younger siblings, in that both children reported a higher sibling relationship quality when the older sibling had a higher parent-child relationship quality than the younger sibling. This suggests that a spillover effect may exist from the relationship between parent and older sibling to other relationships in the family. Future research could investigate the underlying mechanisms of this association and could clarify the direction of the association between the parent-child relationship quality and the sibling relationship quality.Show less