You should put things back into context, because I don't think the parent poster targeted you specifically; most obese people aren't obese because of chronic illnesses but because of lifestyle choices (most of the time, having been fed and addicted to unhealthy food since childhood; thus the lifestyle choice might as well be blamed unto parenting shortcomings, which could be blamed their onto poverty and lack of sanitary regulation on food...).
Some of the most prominent researchers in the US believe that 40-60% of Americans suffer from hypothyroid, possibly in combination with syndrome x. Both of which cruelly cause weight gain AND reduce energy/ability to exercise. That percentage would have to include "most obese people" -- heck, most people, period!
The thing with these 2 issues (hypo/syndrome x) is they are both a cause and a symptom. You can't tell who did what to themselves tabula rasa, or what was done to them (as you point out) by genetics, by childhood, by an environment laden with adrenogenic/estrogenic chemicals, etc. A parent's poor diet changes the expression of genes which can have effects on their children; the additives in food today can have toxic consequences and the food is engineered to be addictive. Sure, personal responsibility. But most people aren't smart enough, or educated enough, or well-positioned enough to fight all the odds against them. And doctors, in my experience, are worse than useless.
