People involve their ancestors in every aspect of culture. Individuals and societies worldwide and throughout history have incorporated ancestors into rituals public and private, religious and secular. Societies often organize their aristocracies, tribes, and other kinship groups around ancestral constructions which are defined through laws and customs governing marriage, naming, guardianship, inheritance, and other social practices. Medical professionals consider ancestral information important to a patient's diagnosis and to the study of disease; many psychiatrists consider one's...