Even one adult homosexual act may threaten the masculine gender identity of American males, and raise the question of their homosexuality. However, fieldwork in Northwestern Mexico revealed a different belief system. A Mestizo Mexican male's masculine gender identity is not threatened by homosexual acts as long as he plays the insertor sex role; only the male insertee, playing a female sex role, is considered homosexual. An analysis of the Mexican data suggests that bisexual behavior is thus more easily accepted by Mestizo Mexican males and is more widely practiced in that region of Mexico than in the United States.