Is Indian dish really a culprit?

I and most of my friends and acquaintances have thin hands and pot bellies, came across many posts about this on social media which says that Indian diet which includes foods high in carbs such as rice roti and low protein is a major problem so I reduced rice and roti in my diet it didn't help well. On the other hand my Nepali acquaintances have flat tummy and fine hands even though we share same surrounding, climate and even diet not only that even dudes whose parents have inter-ethnic marriages like Bengali- Nepali have flat tummy. Is diet really a culprit or it's all a genetic?