Growing up poor does have an effect on eating habits, that's for sure.
I'm careful about what I put on my plate, because I will clean it, for example. No one ever told me about starving children elsewhere as a child, either. But while we were never quite truly food insecure, in my early childhood we had nothing extra at all, and much of what we did have was what my mother canned from the gardens in summer. On the bright side, it meant that I never was a picky eater (one single exception: eggs are foul unless hard boiled). My father was actually hungry as a child; I knew what it meant, but never quite got there, though in retrospect I know my mother occasionally went hungry so that I (and my father, who had to have the energy to work) would have enough. By the time I was old enough for school, this had pretty well changed, but the early impressions stick.
My husband, on the other hand, was raised by his grandfather, who very nearly starved during the depression, and had significant food insecurity/ insufficiency as a child and teenager himself. Another reason I'm careful about what I put on my plate is that if I don't finish it, he will, even if he actually hurts himself, because you don't waste food. You don't know when you will get more, after all. That sort of thing is ingrained and I don't think logic can change it. Like his father and his grandfather before him, he gained a great deal of weight in boot camp because of how well they feed new recruits.
This history could, of course, lead us both into significant trouble if we aren't careful, especially given that, in part, I learned to cook from my grandmother, who raised eleven children and still cooked for a herd; I have trouble with cooking for two, though I think I naturally tend toward cooking for about four, not the thirteen she fed. We manage this by keeping a deep freezer for leftovers and bulk purchases. (This also helps with the anxiety around food we both otherwise experience, and it lets me take advantage of deals.) Psychologically as well as literally, food that's going into the freezer for later is not wasted. Much of the time, I go ahead and package the leftovers before I serve any food; that helps, too.
So far, we've both avoided anything more than very minor cosmetic extra weight -- he carries enough muscle mass that his BMI is high, but body fat is just under 20% based on the Navy calculations, a little higher than the actual percentage, likely, because of his upper-body muscle mass. My BMI is in the acceptable range, but I would like to lose a pants size; body fat per the Navy has me at 21%, which I think is a little lower than the truth.
But if I weren't constantly mindful, or if we were still poor, or even if we didn't have a deep freezer because of financial or space constraints... well. I think the ingrained patterns of thought from both of our childhoods, coupled with the abundance now available so cheaply in America, would lead us into serious trouble. Him especially, both because the hunger in his and his family's past was more serious and because his background is not rural but town, which limited the options for getting food without money. It's hard for me to judge obviously poor people who are overweight, especially if they're older than 40-45.
