Recent studies have shown that variation in political attitudes and participation can be attributed to both genes and the environment. This finding raises the question of why genes matter to participation, and by which pathways. Two hypotheses suggest that feelings of civic duty and sense of...

Twin studies provide an important possibility for demographers to analyze patterns of heritability and to estimate structural models with controls for endowments. These possibilities are increasingly used in the context of fertility and related behaviors. A close congruence between the fertility...

Cause-specific mortality data on Danish monozygotic (MZ) and dizygotic (DZ) twins are used to analyze the influence of smoking and body mass index (BMI) on heritability estimates of susceptibility to coronary heart disease (CHD). The sample includes 1209 like-sexed twin pairs born between 1890...

Twin studies provide an important possibility for demographers to analyze patterns of heritability and to estimate structural models with controls for endowments. These possibilities are increasingly used in the context of fertility and related behaviors. A close congruence between the fertility...

A mixture model in multivariate survival analysis is presented, whereby heterogeneity among subjects creates divergent paths for the individual's risk of experiencing an event (i.e., disease), as well as for the associated length of survival. Dependence among competing risks is included and...

In this paper we use new methods and data to reassess the relationship between the age at first birth and completed fertility. In particular we attempt to properly estimate the postponement effect, i.e., the reduction in fertility associated with a delay in childbearing, using a sample of Danish...

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...