Intergenerational Transmission of Multipartner Fertility

Using data from administrative registers for the period 1970–2007 in Norway and Sweden, we investigate the intergenerational transmission of multipartner fertility. We find that men and women with half-siblings are more likely to have children with more than one partner. The differences are greater for those with younger versus older half-siblings, consistent with the additional influence of parental separation that may not arise when one has only older half-siblings. The additional risk for those with both older and younger half-siblings suggests that complexity in childhood family relationships also contributes to multipartner fertility. Only a small part of the intergenerational association is accounted for by education in the first and second generations. The association is to some extent gendered. Half-siblings are associated with a greater risk of women having children with a new partner in comparison with men. In particular, maternal half-siblings are more strongly associated with multipartner fertility than paternal half-siblings only for women.