Previous studies on how family complexity affects children’s development have focused on the union status of parents and their relationship to the child.
But, most young children in complex sibling relationships live with both of their own biological parents or with a single mother, not with step-parents.
And even though siblings are often a child’s most important peer relationship, the role siblings play in each other’s lives has not received much attention.
For the study, researchers analyzed data from a nationally representative sample of approximately 6,500 US children and their families from the Early Childhood Longitudinal Study.
About one in six children in the United States—more than previously thought—live with half- or step-siblings just before starting kindergarten. And new research suggests these children behave more aggressively more often, on average, than other children do.