Sibling birth order and behaviour

Previous research looking at the sibling dynamic has shown how influential having a brother or sister can be throughout one’s lifetime. Characteristics such as delinquency, educational attainment, and emotional regulation can be attributed to the sibling relationship – all features that are explored in a new body of research. Published for the journal Child Development, a team from several prominent universities in the United Kingdom used longitudinal data from the Millennium Cohort Study to determine how influential birth order can be on child behaviour. In total,18,552 children from England, Wales, Northern Ireland, and Scotland make up the cohort – 70.2% of which live in families with 2-3 children. To understand the dynamic between the youngest and oldest siblings at different ages in middle childhood, researchers measured both problem and prosocial behaviour using the ‘Strengths and Difficulties’ Questionnaire in two different waves. Twenty-five questions reported in the form of a Likert scale were used, of which five subscales emerged: emotional problems, peer problems, conduct problems, hyperactivity, and prosocial behaviour. Results found that when families had two children, the oldest presented “greater within-person stability”, meaning their behaviour was less flexible or receptive to intervention over time. Families with three siblings found “there were differences between siblings in the stability of problems but not prosocial behaviour”, indicating that more siblings may lead to higher levels of equality amongst the group. For more information, click here.