Birth weight and schooling and earnings: estimates from a sample of twins

Based on analysis of a sample of twins, this study suggests that birth weight is not related to levels of schooling, that it plays only a minor role in the determination of earnings, and that ability differences that are not removed in the within-twins model of earnings are not biasing the results in twins studies such as Ashenfelter and Krueger [Ashenfelter, O., Krueger, A., 1994. Estimates of the economic return to schooling from a new sample of twins, American Economic Review, 84(5) pp. 1157-1173].