Educational Differences in Completed Fertility: A Behavioral Genetic Study of Finnish Male and Female Twins

Despite the large body of research on educational differences in fertility, how genetic and environmental influences may contribute to educational differences in completed fertility is not well understood. This study examines the association between educational level and completed fertility in a sample of Finnish male and female twins born between 1950 and 1957 with register-based fertility follow-up until 2009. The results show that poorly educated men and highly educated women are least likely to have any children and have lower completed fertility in general. Behavioral genetics analysis suggests that the association between education and having any children in both sexes is influenced by factors shared by co-twins and that these factors are genetic rather than common environmental. No evidence of a causal pathway between education and having any children independent of these shared influences is found. These findings suggest that familial factors may play a role in the process through which educational differences in completed fertility are formed.     

Multiple Measures of Fixation on Social Content in Infancy: Evidence for a Single Social Cognitive Construct?

The preference of infants to fixate on social information in a stimulus is well known. We examine how this preference manifests across a series of free‐viewing tasks using different stimulus types. Participants were thirty typically developing infants. We measured eye movements when viewing isolated faces, faces alongside objects in a grid, and faces naturally presented in photographed scenes. In each task, infants fixated social content for longer than nonsocial content. Social preference scores representing distribution of fixation to social versus general image content were highly correlated and thus combined into a single composite measure, which was independent of demographic and behavioral measures. We infer that multiple eye‐tracking tasks can be used to generate a composite measure of social preference in infancy. This approach may prove useful in the early characterization of developmental disabilities.     

Education,Other Socioeconomic Characteristics Across the Life Course,and Fertility Among Finnish Men

The level of education and other adult socioeconomic characteristics of men are known to associate with their fertility, but early-life socioeconomic characteristics may also be related. We studied how men’s adult and early-life socioeconomic characteristics are associated with their eventual fertility and whether the differences therein by educational level are explained or mediated by other socioeconomic characteristics. The data on men born in 1940–1950 (N = 37,082) were derived from the 1950 Finnish census, which is linked to later registers. Standard and sibling fixed-effects Poisson and logistic regression models were used. Education and other characteristics were positively associated with the number of children, largely stemming from a higher likelihood of a first birth among the more socioeconomically advantaged men. The educational gradient in the number of children was not explained by early socioeconomic or other characteristics shared by brothers, but occupational position and income in adulthood mediated approximately half of the association. Parity-specific differences existed: education and many other socioeconomic characteristics predicted the likelihood of a first birth more strongly than that of a second birth, and the mediating role of occupational position and income was also strongest for first births. Relatively small differences were found in the likelihood of a third birth. In men, education is positively associated with eventual fertility after controlling for early socioeconomic and other characteristics shared by brothers. Selective entry into fatherhood based on economic provider potential may contribute considerably to educational differentials in the number of children among men.