Understanding the sources of individual differences beyond social and economic effects has become a research area of growing interest in psychology, sociology, and economics. A quantitative genetic research design provides the necessary tools for this type of analysis. For a state-of-the-art...

Evidence of assortative mating according to personality was reported in a previous SOEP-based study (Rammstedt & Schupp, 2008). Based on population representative data of almost 7,000 couples, high levels of congruence between spouses were found, which increased with marriage duration. Almost...

Abstract This paper examines the extent to which quality characteristics of early childhood education and care (ECEC) experienced at ages 4–6 influence externalizing problems at ages 6–8. Based on a random sample of 713 same-sex twins (55% female, 41% with a migration background) in 364 ECEC...

While the health benefits of breastfeeding for both mothers and children are well known, breastfeeding may make it difficult for mothers to return early to the labor market. Maternity and parental leave regulations have been designed to reduce this conflict. In 2007, Germany put into effect a...