Consanguinity and the developmental origins of health and disease
School of Medical and Health Sciences
Background: Consanguineous marriage is strongly favored in many regions of the world, despite the prevalent Western belief that the progeny of close kin unions experience developmental disorders and premature mortality. Objective: We outline an alternative perspective on the association between consanguinity and disease, in terms of life history theory and the developmental origins of health and disease. Methods: Meta-analyses of 64 studies across 14 countries and four continents were performed, comprising some five million births to first-cousin, second-cousin, and nonconsanguineous couples. Results: First-cousin marriage was associated with a mean increase of 3.7% in all-causes mortality, which is significantly lower than the large majority of previous reports. First cousins also married younger and showed greater fertility (P<.0001), possibly reflecting arranged marriage and the maintenance of family property. Conclusions: These findings are consistent with predictions from life history theory. We propose that close kin unions may maximize current reproduction while minimizing reductions in offspring reproductive value under conditions of chronic intergenerational poverty and inequality.