Arising of Man-Made Twins and the One-Child Policy

Wei Huang, Harvard University

This paper documents the rapid rising of twins rates and increasing of different-gender twins proportion in past three decades in China, and mainly analyzes the one-child policy’s role in it. Firstly, OLS estimates suggest that regulatory fine is positively associated with twins rate, especially different-gender twins, and our preferred model predicts that one-child policy fine can explain up to one quarter of the twins rate increase. Furthermore, we also provide evidence that increasing policy fine is remarkably associated with increase in same-gender twins’ height difference but not significantly related to that of different-gender twins', which is consistent with the hypothesis that one-child policy stimulates people’s incentive to give birth to twins by taking fertility drugs or using biological embryo technology.