OBJECTIVE: This study investigated the relationship between eating and weight behaviors and functioning in individuals' families of origin. METHOD: Subjects were 237 women and 242 men enrolled in the RENO (Relationship of Energy, Nutrition, and Obesity) Diet-Heart Study, a prospective 5-year study of the effects of weight fluctuation on cardiovascular disease risk factors in normal weight and obese adults. Variables of primary interest included subjects' body mass index (BMI), age of onset of obesity, eating attitudes, lack of control while eating, and family functioning. RESULTS: In men, higher family cohesion was related to healthier eating attitudes and better control over eating, controlling for age, BMI, and adaptability, whereas higher adaptability (changing rules and poor leadership) was related to earlier onset of obesity and more disturbed eating attitudes. Cohesion and adaptability were not related to body weight or eating variables in women. DISCUSSION: The lower societal pressure on men to be thin may increase the importance of family factors in influencing their shape and weight.