Siblings and Childhood Mental Health: Evidence for a Later-Born Advantage

David W. Lawson, London School of Hygiene and Tropical Medicine (LSHTM)
Ruth Mace, University College London

The social and health sciences have often emphasised the negative impacts of large family size and late birth order on childhood. Few researchers have however quantitatively assessed how siblings may influence indicators of mental health, where it is conceivable that social interactions with siblings may have a positive influence. Using data from the Avon Longitudinal Study of Parents and Children, we explore the effects of family structure on a multidimensional index for childhood mental health; the Strengths and Difficulties Questionnaire. We demonstrate a significant socio-economic gradient in mental health, but little evidence for negative effects of large family size. Rerunning this analysis to examine birth order, a much clearer pattern emerges; older siblings exert a relatively positive influence and younger siblings a negative influence. This suggests that being born into a large family, providing the child is not joined by subsequent siblings, may carry important benefits unconsidered by past research.