You can’t deny that genetics also plays a role in determining body fat. I’m no biologist, but I know that a family with a history of obesity will likely produce fat children. And this is not simply because they pass their lifestyle onto their kids.
Also, not everyone who is obese eats too much. Some people simply can’t burn calories fast enough to counteract the caloric intake necessary for survival.
As to the “race” differences, Darwinian genetics plays a role, or played a role, rather. A lot of Africans, especially in the central countries, are tall, whereas a lot of people in the Europe are short. The bigger Africans would need more food, but if both eat the same amount of food, the shorter Europeans will gain more fat. Also, the climate is different. Perhaps the colder North European air would make fat insulation necessary.
Now, I want to make an important statement. “African American” is not a race. It is a heritage. Race has nothing to do with differences in corporal generalities except for skin, hair, and eye color. You really should have asked if the native heath of your ancestors makes a difference in your body fat. In my opinion, it does.