Parents making their kids fat is abuse. End of story.
People being fat is personal choice and will power more than genetics. Fat people have the choice to be fat. No one's born fat. It's something that's learned.
Well... genetics is a thing. For example, It's really hard for one of my friends to gain weight.
Because of the stomach problems. And he can eat only specific healthy food.
He always tells me that he wishes to be fat at least for one day.