Food Left On Plate

Usual noisy Friday night supper tonight at the brother-in-law's. It's bwo's birthday tomorrow so a cake was brought out and a fuss was made. I noticed something interesting about myself. I have a real problem with people taking too much food and leaving it on their plates. Bdo has always had real case of eye larger than stomach syndrome. It makes me nuts. So I always have to eat her leftovers. I started thinking about this tonight. What's my problem? Where does this obsession about not leaving anything on the plate come from? I wasn't in the holocaust or anything. I have absolutely no problem chucking dead food out of the fridge. In fact I enjoy it - we do often. Its only food left on the plate that irks me. And when I think about it, I have no problem with people leaving leftovers on their plates in a restaurant, its only when someone takes more than they will eat that I get very bothered. Clearly some deep Freudian issue here - I wonder what it is.