The effect of the number of siblings on education in sub-Saharan Africa: evidence from a natural experiment

The objective of this paper is to investigate the effect of the number of siblings on education in urban sub-Saharan Africa. The birth of twins is considered as a natural experiment that affects the number of siblings but has no direct effect on education. This event is used as instrumental variable in a two-stage least-squared estimation approach to investigate the causal effect of the number of siblings on school achievement. Equations are estimated on subsamples of singleton children born before the twins. The results show that an exogenous fertility increase significantly inhibits human capital accumulation. However, the magnitude of the marginal effect seems small: one additional sibling decreases the total number of school grade by nearly one-tenth. In a context of high fertility, the total effect might become very detrimental.