The reality is that unless you've been 50-100 pounds overweight all your life and worked your way down to a healthy weight for at least 5 years, your opinion about what makes people fat is worth less than dog shit.
I am six feet. I lost 4 inches - 40 waist size to 36 - in one year.
What did I do?
Daily 40-50 minute brisk walking (jogging might damage knee joints), some stomach crunches and push ups. The same time reduced carbohydrates (which was easy as a South Indian - all I had to do was reduce - not avoid - the amount of rice in the diet.) I have not avoided sugar. I take alcohol, though now a days its rare. (In India good beer is insanely expensive, so you don't feel having one.)
Was the exercise regime easy to follow? Yes...it was, at least for me. The exercise gave me so much energy it became some type of addiction.
Can anyone do the same? Yes. But they won't. The key is both exercise and reduced carbs - a mix not easy for everyone to adopt. I regularly see people start on a routine and drop after a few days. And I also notice long time dedicated walkers and joggers.
Is genetics to blame if you cannot be disciplined? I have no idea. But I don't expect everyone to have willpower and focus for such situations. May be I was lucky.