Social learning plays a crucial role in development, enabling children to acquire knowledge from both adults and peers. Within this process, siblings may provide unique opportunities to practice with social learning at an early age. This raises the question whether only-children use social information differently than children with siblings. Previous research has reported lower social capacities in only-children compared to children with siblings. However, evidence remains inconclusive as to whether birth order (divided into only-children, first-borns and later-borns) moderates developmental changes in social learning. Therefore, this study examined whether children’s social source preference (parents versus peers) and the extent to which children adjust their behavior based on social information, differ as a function of age and birth order. Data were collected in the science museum NEMO, where children aged 6 to 12 and their parents were asked to voluntarily participate in an estimation task (BEAST). Afterwards, a logistic and a linear regression analyses were conducted, to test the effects of age, birth order and their interaction. It was expected that only-children and first-borns would show a stronger preference for learning from parents and exhibit greater adjustment toward parental information than later-born children. However, no significant effects of birth order or interactions with age were found. In contrast, younger children showed more reliance on social information than older children. These findings suggest that developmental changes in social learning are primarily driven by age rather than birth order.