Whenever biologically unrelated mates become scarce, consanguineous marriages become a potential option for procreation. Despite the genetic harms caused by inbreeding, kin unions still produce more viable offspring than the alternative: remaining single. We present a family that, due to loss of its high social status, was unable to find unrelated mates for their children. The solution was a marriage arranged between first cousins, which produced five children with genetic disorders. By the time these defective children became adults, the social status of the family improved. Thus, for their four unfit daughters, the parents could arrange marriages with healthy and biologically unrelated men. These unions produced four healthy children. We analyze the interaction of mate choice, sexuality, inbreeding avoidance, altruism and parental investment to establish that close-kin marriages are an adaptive response to a shortage of unrelated mates.