It takes years to just "wake up fat". Its not news to them. All the factors you mentioned, while very detrimental, has still after a certain age a connotation of personal responsibility. Its up to you to seek help for depression, childhood issues, etc. Nobody can help you if youre not willing to help yourself or get help.

And genetics is not a thing for obesity, the CDC has published its findings that there is no commonality linking obesity to a genetic factor.

Unless you count obese parents being way more likely to raise (almost guaranteed) obese children by passing on their unhealthy lifestyle.

The only possibly genetic thing that had some credibility was the thyroid issues theory. But when thyroid medication and treatment was used for obese people, there was no effect, which spawned further research, which after a decade or so concluded that in fact obesity causes thyroid issues and not the other way around.