Twin births are often construed as a natural experiment in the social and natural sciences on the premise that the occurrence of twins is quasi-random. We present new population-level evidence that challenges this premise. Using individual data for 17 million births in 72 countries, we...

Twin births are often used to instrument fertility to address (negative) selection of women into fertility. However recent work shows positive selection of women into twin birth. Thus, while OLS estimates will tend to be downward biased, twin-IV estimates will tend to be upward biased. This is...

Twin births are often used to instrument fertility to address (negative) selection of women into fertility. However recent work shows positive selection of women into twin birth. Thus, while OLS estimates will tend to be downward biased, twin-IV estimates will tend to be upward biased. This is...

The importance of non-cognitive skills in determining long-term human capital and labor market outcomes is widely acknowledged, but relatively little is known about how educational investments by parents may respond to children’s non-cognitive characteristics. This paper evaluates the parental...

Twin births are often construed as a natural experiment in the social and natural sciences on the premise that the occurrence of twins is quasi-random. We present new population-level evidence that challenges this premise. Using individual data for 17 million births in 72 countries, we...

Son biased investments are common in many Asian countries where sons are customarily responsible for providing old age support to parents. Using data from the China Health and Retirement Longitudinal Study, I find that parents invested nearly twice more in sons than in daughters in terms of...