UCLA

Siblings play an important role in shaping the developmental trajectories of individuals with autism spectrum disorder (ASD). Having siblings has been associated with better social communication, non-verbal communication, and theory of mind abilities in ASD. However, little is known about the impact of siblings on adaptive skill growth over time, even though adaptive behavior competencies are among the strongest predictors of positive outcomes in ASD. This study examined the influence of sibling constellation factors, including the presence of siblings, position in birth order, gender of closest-age sibling, and gender match of sibling dyad on the adaptive behavior trajectories of individuals with ASD and non-spectrum disorders from ages 9-26 years. Participants with one or more siblings, regardless of birth order position, experienced faster growth rates in adaptive behavior than participants without siblings. Additional benefits were noted when participants’ closest-age siblings were male and when participants were gender-matched with their closest-age siblings.