Sibling Relationships and Social Development in Youth and Emerging Adults: A Self-Determination Theory Approach

This study aimed to examine an integrated model of the mediation role of need satisfaction and frustration in the association between the sibling relationship and interpersonal competence and social anxiety in young adults and their siblings. In a sample of 1621 pairs of siblings with a range age between 16 and 30 years old, the actor-partner interdependence mediation model showed that (a) a positive sibling relationship promotes need satisfaction, while a negative relationship promotes need frustration; (b) need satisfaction to promote interpersonal competence, while need frustration promote social anxiety; and (c) a mediation role of basic need in the association between sibling relationship and social anxiety and interpersonal competence. The need satisfaction perceived by the older siblings is negatively related to social anxiety and positively related to the interpersonal competence of younger siblings. These results showed the importance of focusing on sibling dynamics in the family context using a SDT approach.