Ethnocentrism is the judging of other cultures as abnormal and inferior when compared to one's own culture. "Ethnocentrism may result from the combined effects of several widespread psychological phenomena: an in-group/out-group psychology” and a disposition to group nepotism, a psychological adaptation that arises from "enforcing an ethic of unidirectional altruism toward kin." Numerous studies have shown that when people are divided into groups, they tend to favor members of their own group over outsiders. This tendency, and ethnocentrism itself, may be a function of evolution, as it is advantageous for individuals to support close relatives or tribe members over outsiders.