Cognatic descent is more flexible than unilineal descent because it allows people to track their relationships to the families of each parent. Slightly less than half the world’s peoples traditionally use or have used this system; although people in the U.S. typically use the last name of the male parent in naming (which seems to imply unilineal descent), they’re actually interested in (and make social and economic use of) the relations of both parents’ families, so U.S. residents actually practice cognatic descent.According to the passage, cognatic descent is the practice of tracing