Is there a genetic component to obesity, or is it mostly environmental/behavioral?

Both play a real role, and they interact rather than being separate causes. There's a documented genetic and family component to obesity risk, affecting things like appetite regulation, metabolic rate, and fat storage tendencies. Environment and behavior (food availability, activity levels, sleep, stress) then interact with that genetic baseline to determine actual outcomes. It's generally described as a complex condition with both genetic predisposition and environmental influence, not a purely one-or-the-other situation. References: https://obesitycanada.ca/healthcare-professionals/adult-clinical-practice-guideline/