Not. My wife and kid don't have this problem. She could have 3 peas on a plate and leave 1. I'm in the same boat as the OP.
Comfort associated with food, learned early I would expect.
My solution was for it not to be around. Difficult with a wife and kid. More cardio for me.
It's natural to the same degree it is in other species. Some animals, given "unlimited" and constant access to food, will gorge themselves fat. Others, even of the same species and in the exact same situation, will moderate and pace themselves quite naturally.
You can have dogs that, if healthy (as is, no temporary/permanent illness), will eat everything given to them at each meal and not even understand that their weight is an issue. Yet other dogs will quickly adjust and only eat how much they want/need at any given time, and will end up grazing (and we humans adjust to that by filling the bowl when needed, not at set times); such dogs usually are much thinner (healthy weight). It thus takes a conscious effort on OUR part to meter out food to pets that do have an issue with food, which is strange when you think about it.
Honestly, I can't really say why this phenomenon is such.
It makes sense it's sort of an instinct, in that you should eat what is available now, and get as much as you can stomach, because you cannot guarantee what lies around the corner tomorrow. The fatties, as long as they have access to a water supply, will survive longer if their is a sudden disappearance in food. That can be a good survival tactic... if food isn't guaranteed to be accessible.
But many of us, either consciously or not, adjust and our brain gets into a very strange state for an animal: a reliance on promises and habits, where our brain thoroughly believes we'll be able to have food whenever we need it, without worries. But it results in a good equilibrium, and we don't even have to exert much effort to ensure food is actually on hand. No hunting, only minimal-effort gathering (though funded through paid slavery).