The Impact of Sibling Sex Composition on Women's Educational Achievements: A Unique Natural Experiment by Twins Gender Shocks

In a pro-male biased society, brothers may reduce the parental investment received by female siblings, if parents face time or financial constraints. But brothers may also cause positive externalities. Using more than 12,000 firstborn twins from a highly sex-imbalanced economy, Taiwan, we test if women have fewer opportunities to attend college if they have a brother rather than a sister. To minimize the problem of sex selection, we exploit the fact that twin sex is random given the sex of the other twin, once we limit the data to time periods in which abortion was illegal and technology was unavailable to abort one of the two twins. We show that the birth of a male sibling, relative to a female, has almost no impact on women's or men's college enrollments on the average. If there is any effect, it is small and imprecise. Our results point to the importance of accounting for positive externalities (e.g., decreasing family size) created by a son's birth, in studies on sibling rivalry.