yes you are correct, our genes are what determines weight in realtion to the foods you eat. it affects your bodies ability to metabolise those foods , etc
but most of the foods you eat, over 90% of what is available in walmart for instance, is industrial manufactured trash that no human except perhaps escaped roswell experiemnts and MBAs can metabolise correctly
this is compounded by modern trash propaganda telling people not to eat meat, to replace meat with synthetic mineral oils and watered down oats for $500 a litre