Yes I would agree with you to an extent. At the end of the day though if you are someone that sits on your arse all day (regardless of age), snacking on sweets or other "comfort foods", are too lazy to cook something nutritious then you really do only have yourself to blame as far as I am concerned and I guess with young children a large portion of the blame would rest on their guardians.
I hate it when I hear of people blaming others for their weight. Personally I think they should just take responsibility for their lives, stop eating like a pig and get some exercise.
Sorry if I offend any one, just my honest opinion. Not really directed at anyone.