Choice of kin in consanguineous marriages: Effects of altruism and ecological factors

Background. Despite being associated with multiple genetic problems, consanguineous marriages continue to remain extremely prevalent worldwide. Studying the variation of kin preferences in diverse inbred societies may provide some answers to this paradox. Aim. To find the reasons for specific kin choice in different geographical areas of the world. Method. We used a set of sociobiological rules (kin altruism, sexuality and inbreeding avoidance) and ecological constraints (e.g. tribal warfare, food availability) that influence human behaviour. The cumulative help that the extended family can provide to a nuclear family was calculated using the coefficient of relatedness between kin in different types of consanguineous families. Results. The maximum potential support for kin markedly varied between different types of consanguineous marriages. Overall, members of consanguineous families received up to two-and-half times more support than members of non-consanguineous families. In various inbred cultures, preference for a specific type of kin was determined by prevailing ecological limitations and sociobiological factors interacting in a complex manner. Conclusion. In different inbred populations, the ideal kin for a consanguineous marriage is the one who can provide the most altruistic support; however, this choice is influenced by biological rules of behaviour and ecological constraints.