Individual versus group selection results in a mix of altruism and selfishness, of virtue and sin, among the members of a society.

Wilson is summarizing a central claim of multilevel selection theory: natural selection can favor traits that benefit individuals (self-interest) and, under some conditions, traits that benefit the group (altruism). In human societies this produces a stable tension rather than a single moral direction—cooperation, sacrifice, and “virtue” coexist with competition, cheating, and “sin.” The line frames morality not as an anomaly outside biology but as an emergent outcome of evolutionary pressures operating at different levels of organization. It also implies that social systems must manage, not eliminate, this dual inheritance: institutions and norms can amplify cooperative tendencies while constraining selfish ones.