Historically, the weakening of ties among extended family has been associated with development, urbanization and economic growth. The causal relationship underlying this link, however, has been unclear. Kinship ties may react flexibly to changes in incentives rather than being fundamental causes of economic outcomes.
A new study by briq postdoc Arkadev Ghosh, “Sam” Il Myoung Hwang and Munir Squires, using U.S. state bans on cousin marriage, supports the hypothesis that tightly knit family structures impede development. To measure cousin marriage, the authors utilize the excess frequency of same-surname marriages, a method derived from population genetics, which they apply to millions of marriage records spanning the 18th to the 20th century. Using census data, they first show that married cousins tend to reside in rural areas and hold lower-paying occupations.
The researchers then employ an event study analysis to investigate the effects of cousin marriage bans on outcomes for birth cohorts subjected to these regulations. They discover that such bans prompt individuals from families with high rates of cousin marriage to leave farms and migrate to urban areas, and they also gradually shift to higher-paying occupations.
Additionally, the researchers observe increased occupational and geographical dispersion — individuals from these families reside in a broader range of locations and pursue more diverse occupations. The findings indicate that these changes primarily arise from the social and cultural implications of dispersed family ties, rather than genetic factors. Notably, the bans also lead to a higher number of individuals residing in institutional settings for the elderly, infirm, or destitute, suggesting reduced support from relatives.
The study (see pre-publication version here) has now been published in the Quarterly Journal of Economics.