Social and genetic factors influencing human fertility behavior

I will present on the interplay between genetic and social factors in human reproductive behavior. First, I will introduce our recent findings on the role of genes in human reproductive behavior (GWAS). Second, I will... [ view full abstract ]

I will present on the interplay between genetic and social factors in human reproductive behavior. First, I will introduce our recent findings on the role of genes in human reproductive behavior (GWAS). Second, I will illustrate how genetic designs can help to get a better understanding of the social determinants of reproductive behavior. See abstract below. 

Education and postponement of fertility.

A large body of literature shows a positive relationship between education and age at first birth. However, this relationship may in part be spurious due to family background factors that cannot be controlled for in most research designs. We investigate to what extent education is causally related to later age at first birth in a large sample of female twins from the UK (N=2,752) and a large sample of siblings in the Netherlands (N=32,000). For the UK, we present novel estimates using within-identical twin and biometric models. Our findings show that one year of additional schooling is associated with about half a year later age at first birth in OLS models. This reduced to only 1.5 months for the within-identical twin model that controls for all shared family background factors (genetic and family environmental). Biometric analyses reveal that it is mainly influences of the family environment– not genetic factors – that cause spurious associations between education and age at first birth. Lastly, we demonstrate using data from the Office for National Statistics that only 1.9 months of the 2.4 years of fertility postponement for birth cohorts 1944-1969 could be attributed to educational expansion based on these estimates. We conclude that (the rise in) educational attainment alone cannot explain differences in fertility timing (between cohorts). The results for the Dutch sample using siblings yields similar results.