This study investigates the effects of cultural norms on family health history (FHH) communication in the American, Chinese, and Korean cultures. More particularly, this study focuses on perceived family boundaries, subjective norms, stigma beliefs, and privacy boundaries, including age and gender, that affect people's FHH communication. For data analyses, hierarchical multiple regression and logistic regression methods were employed. The results indicate that participants' subjective norms, stigma beliefs, and perceived family/privacy boundaries were positively associated with current FHH communication. Age- and gender-related privacy boundaries were negatively related to perceived privacy boundaries, however. Finally, the results show that gendered cultural identities have three-way interaction effects on two associations: (1) between perceived family boundaries and perceived privacy boundaries and (2) between perceived privacy boundaries and current FHH communication. The findings have meaningful implications for future cross-cultural studies on the roles of family systems, subjective norms, and stigma beliefs in FHH communication.