Background Excessive bodyweight contributes to a myriad of risk factors for chronic diseases, and multiple reports have demonstrated that parents influence the development of their children's behaviors that contribute to bodyweight. However, studies that include considerations for cultural influences are limited, and methodology that considers direct reports from young adults and their parents across cultures does not exist. Methods A sample of young adults (N = 327) and their parents in the U.S. and in China were recruited and completed a series of questionnaires in two cycles (2010 and 2014). With correlation and multiple regression analyses, parents’ characteristics, behaviors, and parental authority styles were examined and compared to weight‐related health behaviors and bodyweight of their young‐adult children. Additionally, similarities and differences of parental influences between the two cultures were explored. Results Parents’ body mass indexes (BMIs) and dietary behaviors were positively associated with those of their young adult children in the mixed‐culture sample (P < .001 for both). When controlling for gender, at high levels of authoritarian and permissive parental authority, the relationships between young adults' and their parents’ BMIs were negative for U.S. participants and positive for Chinese participants (P < .05 for both). Further, at high levels of authoritarian parenting, the relationship between young adults' and their parents’ dietary consumption behaviors was negative for U.S. participants and positive for Chinese participants (P < .001). Conclusions This study provides evidence that the development of life‐long health behaviors that contribute to BMI are significantly influenced by parents’ behaviors and parenting styles. Moreover, an interaction of parental characteristics and cultural norms is indicated.