The study takes advantage of a convenient natural experiment. There are two tribes in Northeast India that are very similar in many ways. They both share the same agrarian lifestyle and diet, reside in close proximity, and DNA tests indicate that they are closely related. The biggest difference between them is culture. Among other differences, the Karbi are patrilineal; women do not typically own land, and the oldest son inherits the family’s property after the death of the parents. The Khasi could not be more different in this regard. Men are not allowed to own land at all, any money or goods earned by a male are handed over to his wife or sister, and inheritances go to the youngest daughter in the family.