It seems that Obesity in children is due to many causes however genetic cause is still the most important factor at all.
The child may inherit the obesity character from on of the parents or grand parents.
The second cause of obesity is still eating fast foods. since they contain high level of energy due its fat content thus it provide the body with too much calories way beyond its need for example drinking soda which contain high level of sugar.
Ignoring to provide healthy diet to child has a catastrophic impact on the obesity thus changing wrong dietary habbits is ofcourse considered crucial and that occurs practically by replacing the high energy food by sweat fruits, salad and vegetables.
Practicing exercise is essential to induce balance between metabolism within the body and food intake.