I lived through exactly the OP's situation as a 10yo kid.
My mother and I had traveled to her sister's (my aunt's) house. They lived half-way across the country from us so this wasn't an every day thing. Aunt had two kids and some sort of family reunion type day planned. She had gone out and done "special shopping" so there would be food for everyone.
I took a look at what was on the table... There were plates of cut vegetables, ham/roast beef and cheese sandwiches, fruit, hot dogs with ketchup, grocery store fried chicken drumsticks, twinkies, etc.... I started in on the cut vegetables and roast beef. I had some strawberries. I ate more vegetables. I went back for thirds on the vegetables. My aunt watched, aghast, as I ate. Finally she couldn't take it any more and told me that I shouldn't be eating that food. I can't remember exactly what I said in reply but she was more than a bit shocked and lit into my mother to control her son, force me to eat the age appropriate food (to her that was obviously the hotdogs and twinkies as far as I could understand).
My mother replied with something along the lines of, "I believe in letting kids eat what they want to eat."
It went down-hill from there. I remember this part, though, almost 30 years later: Aunt to my mother, sounding indignant, "I don't know what it's like in California, but here in Wisconsin vegetables are expensive!"
In hindsight I suspect the encounter wasn't helped by the fact that when Aunt asked me (before going shopping, I think) what my favorite food was, I had replied, "lobster." Hey, she asked what I liked, not what I had tasted more than once in my life.
The funny part was that I wasn't a skinny kid. My older brother (who didn't like vegetables nearly as much as I did) was a rail, but I was always on the upper end of the weight range. Not fat per se, but not light. In hindsight, I attribute most of my bad eating habbits to one aspect of my upbringing: We lived on a single income in Southern California (where the cost of living was and is high) and my mother had serious health issues of the "multiple surgeries, radiation therapy, etc, starting when I was 5" variety. In other words, we were broke most of the time and didn't have a huge amount of money to spend on food. My mother tried to deal with this by cooking exactly the right amount of food...but if she undershot (and that happened often) were like young birds in a nest at feeding time...the most agressive eats, the others starve. My brother was older by 5 or so years, a natural advantage in those circumstances. I learned that if I took a small serving and wanted more...well, chances are by that time the food would be gone. I learned to eat almost anything that was served and not to be picky. I learned to grab as much food as I could, when I could. Probably great lessons for Grok or whatever, but bad lessons for a kid in our decadent food-rich society.