The occurrence of twin births has been widely used as a natural experiment. With a focus upon the use of twin births for identification of causal effects in economics, this chapter provides a critical review of methods and results.

Using data of adult women from the German Socio-Economic Panel (SOEP), we find that risk tolerance is associated with a higher probability of an out-of-partnership birth. In contrast, we find no association between risk tolerance and the probability of a cohabiting birth.

Most private giving between living generations takes the form of tied transfers, such as help with housing downpayments. We argue that parents provide help with downpayments in order to encourage the production of grandchildren, and that such a subsidization emanates from the demonstration...

This paper provides a first microeconomic foundation for the institution of marriage. Based on a model of reproduction, mating, and parental investment in children, we argue that marriage serves the purpose of attenuating the risk of mating market failure that arises from incomplete information...