What are the causes of Obesity?

It was proved that obesity has genetic basis, but these represent only a predisposition. It means that a person does not develop excess body fat just because it is genetically predisposed, but also because has a wrong lifestyle (overeating and sedentary lifestyle). Then people who are genetically predisposed to obesity can avoid its developing simply adopting an healthy lifestyle. Conversely, people who are not predisposed, they can become obese if they exceed in food and have a sedentary lifestyle.