This essay explores the hypothesis that some sources of family income encourage, while other sources discourage fertility because different sources of family income modify the economic opportunities parents must sacrifice to have another child, or the price of children in terms of parental time and market goods. It measures the household connections between fertility and income in Kenya. It argues that to account for the impact of fertility on society, it is useful to distinguish between genetically determined variation in the supply of births that is more or less random, and behavioral...

This essay explores the hypothesis that some sources of family income encourage, while other sources discourage fertility because different sources of family income modify the economic opportunities parents must sacrifice to have another child, or the price of children in terms of parental time and market goods. It measures the household connections between fertility and income in Kenya. It argues that to account for the impact of fertility on society, it is useful to distinguish between genetically determined variation in the supply of births that is more or less random, and behavioral variation in the demand for births that is coordinated with many other choices parents make over their lifetimes.