First Among Equals? How Birth Order Shapes Child Development

I study how birth order affects children’s academic achievement, personality, and well-being in elementary school. Earlier-born children not only perform better in reading and mathematics throughout elementary school, but they are also more conscientious, agreeable, and emotionally stable, and report higher well-being. Reading ability and conscientiousness – crucial skills for success – appear particularly sensitive to the early childhood environment. These effects are remarkably stable across different groups. I also provide new evidence on the quantity-quality trade-off by showing that family size has a negative effect on earlierborn siblings which enlarges the birth order effect by disproportionately affecting younger siblings.