Unraveling the intergenerational transmission of fertility: genetic and shared-environment effects during the demographic transition in the Netherlands, 1810–1910

Abstract

Differential fertility can be attributed to economic and cultural factors, but the family also plays an important role. Fertility behavior may be transmitted from parents to children through heritable dispositions or via socialization. Previous research has shown, however, that the expression of genetic effects depends on the interplay with the environment. In this article we take a long-term view and examine how the different mechanisms shifted over time and across social and local contexts on the basis of a large-scale database containing 100 thousand sibling pairs born between 1810 and 1870 in the Dutch province of Zeeland, a society undergoing demographic transition and industrialization. Corroborating earlier research, we find a significant increase in the expression of heritabilities and a fading of social influence for women born after the 1840s, who started their reproductive careers during the historical fertility decline in this region. Our study points out that the ‘social control’ of fertility was particularly reduced for women born in towns, women originating from the urban or rural laboring classes, and women from communities with a relatively liberal religious climate. Our findings are in line with research emphasizing the important role played by women in decision-making processes around childbearing, and could indicate the conditions that enhanced women's position in household bargaining during the historical fertility decline.

Keywords:

• intergenerational transmission of fertility
• genetic influences
• the Netherlands
• historical fertility decline
• sibling models
• heritability

Acknowledgements

This study was supported by a VIDI Innovational Research Grant from the Netherlands Organization for Scientific Research, for the project entitled ‘The Power of the Family: Family Influences on Long-Term Fertility Decline in Europe, 1850–2010’ (contract grant number 452-10-013). Earlier versions of this article were presented during the international seminar on ‘The intergenerational transmission of reproductive behavior: comparative perspectives’ (Leuven, Belgium, 9–10 June 2011), organized by the Historical Demography Network, funded by FWO-Vlaanderen and during the international seminar on ‘Combining Biology and Social Science in Life Course Studies’ (Helsinki, 8–9 September 2011, organized by the Network on Quantitative Methods in the Social Sciences, funded by the European Science Foundation. The authors wish to thank the participants of both seminars for their valuable comments and insights.

Notes

1. Other examples of the use of historical databases for the study of intergenerational processes of demographic behavior can be found in the papers belonging to the special issue of Human Nature (2008) that resulted from a workshop on ‘Inherited dimensions of human populations in the past’, which was held in Menorca in 2005.

2. Non-shared environmental influences refer to effects not explained by heredity or by shared environment, including measurement error.