Does Family Size Reduction Improve Intergenerational Educational Mobility? A Fuzzy RDD Analysis of China’s One-Child Policy

This study investigates how smaller family sizes affect educational mobility across generations, using China’s One-Child Policy as a natural experiment. By analyzing data from the 2015 National 1% Population Sample Survey and applying a fuzzy regression discontinuity design, we find that having no siblings positively impacts children’s education and increases the likelihood of upward mobility. The effects are especially significant for daughters, suggesting that less sibling competition particularly benefits girls’ education. Further analysis shows that the effects vary by factors such as urban versus rural households, regions with more balanced gender norms, and families with better pension coverage or higher parental education. These findings illustrate how family structure, combined with institutional and socioeconomic factors, shapes educational opportunities. Additionally, the results enhance understanding of the trade-off between family size and the quality of human capital investment, providing useful insights for policies aimed at improving educational equity in developing countries undergoing demographic changes.