It's extremely probable that obese kids have some kind of trauma or dysfunction at home, so yeah
It really is genes for some people tho. For example -
My sister has always struggled with her weight. I've always been on the thin side. We grew up in the same house so we couldn't have been eating very much different. And I was never especially athletic or active either, so it's not like I was working out regularly. Nor was I ever particularly health conscious or restricting calories. Some people really are unlucky.