Lowest-low fertility, defined as a period total fertility rate at or below 1.3, has rapidly spread in Europe during the 1990s. This article traces the emergence of this new phenomenon to the interaction of five factors. First, tempo and compositional distortions reduce the total fertility rate...

This article investigates the fertility of Danish twins born during the periods 1870-1910 and 1953-64 in order to pursue two central questions for understanding human reproduction: Do genetic dispositions influence fertility and fertility-related behavior? Does the relevance of the "nature...

Economic and rational-choice theories suggest that individuals form unions or have children because these decisions increase their subjective well-being or "happiness." We investigate this relation using within-MZ (identical) twin pair estimates to control for unobserved factors, such as...