The impact of siblings on motor development in the first two years of life – a replication

The relationship between the presence of older siblings and the development of the child in the first two years of life was examined. Children with siblings achieved higher values at birth in terms of Apgar-score, height, weight, BMI and parental satisfaction with the health and development of the child compared to firstborns. However, no differences could be found at the ages of 10-12 months and 14 months. Firstborns reached five fine motor and manual dexterity milestones earlier than children with siblings. In contrast, when mastering 13 gross motor milestones, no differences could be found between firstborns and children with siblings. Motor development at an early age is considered to be largely genetically controlled, analogous to physical development. However, the faster development of the fine motor skills of the firstborns could be related to the fact that parents interact more intensively with their firstborn than with later born children and – unlike gross motor skills – in fine motor skills not only genetic factors but also learning processes are effective from a very early age.