Growth in positive relationship quality with mothers, fathers, and siblings and associations with depressive symptoms and emotionally supportive prosocial behaviors during the transition to adulthood

Despite theoretical underpinnings that social influences increase in salience with age, it is currently unclear how relationships with mothers, fathers, and siblings might change during the transition to adulthood and what roles the quality of those relationships play in young adults’ longitudinal adjustment. Therefore, the purpose of the present study was twofold. Firstly, we explored longitudinal growth in positive relationship quality with mothers, fathers, and siblings across the transition to adulthood. Secondly, we assessed comparative associations between positive relationship quality with mothers, fathers, and siblings and young adults’ depressive symptoms and emotionally supportive prosocial behaviors toward strangers and family members from 18 to 20 years. Participants included 402 young adults (51% female; 69.39% White; Mage at T1 = 18.36 years). Mother‐youth positive relationship quality slightly increased during the transition to adulthood, while both father and sibling positive relationship quality remained stable. Young adults with more positive relationship quality with mothers reported experiencing fewer depressive symptoms, and young adults with more positive relationship quality with siblings were more likely to engage in emotionally supportive prosocial behaviors toward both strangers and family members. The increasing strength of mother‐youth relationships during the transition to adulthood and the comparatively salient role of sibling relationships are highlighted.