What an interesting discussion. I think "blame" is such an angry word. Pointing fingers has never done anything to help me lose weight. It just made me angry. And "fault" is an aloof word. It implies that there is a source. Out bodies just do as they do, they're obedient little creatures and they go with the flow. Give them too much food and they'll store it for you. Give them less and they'll start to need less.
I can't claim to understand genetics. Maybe someone has inherited a medical condition that requires a type of medication that is known to cause gain. I can accept that, that could be something to blame for sure. But I fear that the vast majority of people who say that their genetics play a role the source is their problems are actually behavioral. Last week I took my kid to chucky cheese and happened to see a family who were all obese right down to their 7yr old son. Maybe this family has genetic predispositions for obesity, diabetes, and blonde hair. But I am pretty sure that none if them are genetically predisposed to eat one large pizza each. So when someone says "all the women in my family are obese" it generally means that everyone on that family shares a lifestyle that contributes to their weight. I'd say it'a possible that genetics plays a role if everyone in that family was physically active and ate a healthy diet and was still obese. Yea that would suck genetically - but is that plausible scenario?
The over abundance of processed food and sedentary life styles are solely to blame for why so many people gain weight. The diet culture is another. On one side you have food companies flashing lights and telling you to get in your car and go but as many of their food as fast as possible. On the other hand you have the gazillion dollar diet industry telling you not to trust yourself around food, just eat what they tell you to eat, and when to eat it. Then sit at your computer and get all your Christmas shopping done with the click of a button. Obesity is NOT that complicated.
Eat some real food. Eat it when you're hungry. Stop when you're full. Enjoy it as much as possible. Forget it when it's gone. Go take a walk. These are the rules I live by.
"No matter how developed you are in any other area of your life, no matter what you say you believe, no matter how sophisticated or enlightened you think you are, how you eat tells all." - Geneen Roth