Consistent with lay and professional views, Masters, Johnson, and Kolodny (1985), in an early edition of their human sexuality textbook, presented man-man sex as normal and acceptable but man-boy sex as pathological and unacceptable Despite drawing these moral distinctions, they used a series of examples of socially sanctioned man-boy sex in other cultures to provide perspective on Western man-man sex, suggesting its normalcy and potential to be socially accepted. They ignored these same examples when discussing Western man-boy sex. This paper examines the biased use of cross-cultural and historical data on homosexuality in a sample of more recent human sexuality textbook (n = 18). A brief review of male homosexuality in other times and places is presented which shows the prevalence of man-boy sex, but the rarity of the Western man-man pattern, cross-culturally and historically. This finding further questions the practice of using man-boy examples for Western man-man, but not man-boy, sex. Seventeen of the textbooks in the current sample exhibited the same biases found in the earlier Masters et al. textbook. Only one used man-boy examples in other societies for perspective on Western man-boy sex. It is argued that these biases hinder rather than advance the objectivity that can result from the proper use of cross-cultural and historical perspective.