Kinship is a universal feature of human social life and, in the United States, genealogy is the second most popular hobby. Yet despite this fascination with kinship, a fundamental mystery has been neglected: Do people adopt kinship practices that serve the interests of their genes? Or does culture define kinship practices causing genetic underpinnings to become obscured? This study will explore the congruence between the cultural and genetic spheres of kinship and, in so doing, shed light on the broader relationship between biology and culture. It is a collaborative venture that combines the expertise of a human population geneticist with that of an anthropologist. This interdisciplinary research will introduce state of the art molecular technology to ethnographic field studies and provide a rich ethnographic data set to permit new questions to be asked using genetic sequence data. The study focuses on the Dogon, a traditional millet farming people of Mali, West Africa. The Dogon are ideal for this research because they employ a variety of cultural practices that appear to be reproductively motivated. This research will test the hypothesis that these cultural rules serve the genetic interests of those who enforce them and that they lead to a close mapping of culture onto biology. The study will also test alternative hypotheses about the basis for human cooperation. This objective is significant because it will be one of the first analyses of helping behavior in a human population that uses data on genetic relatedness from DNA sequencing. The broader impacts of the study include the training of American and Malian students in genetic techniques and quantitative fieldwork methods. Medical residents will gain experience in a developing country and share their expertise with a rural African health facility. The results will be disseminated in scientific journals, genetic databases, and a specialized monograph.