Allport estimated that conformity alone underlies roughly half of all prejudiced attitudes

Evidence

In chapter 17, titled “Conforming,” Allport (1954/1979) targeted conformity as a primary cause of prejudiced behaviors and belief, stating, “about half of all prejudiced attitudes are based only on the need to conform” (p. 286). By the 1950s, psychologists had long known that people adapt their behavior to the social norms of the situation; Allport applied this principle to prejudice. Relying both on anecdote and empirical research, Allport cogently argued that conformity was one of the most important causes of prejudice. — , Rudman, Laurie A - On the Nature of…, 1888