It's not really anything all that gross to a non-vegetarian --- they boil bones and other such parts from meat processing that aren't suitable for food to make gelatin. A vegetarian who doesn't eat meat for ethical/moral reasons would object, but an omnivorous human would not.

Saying it's made from "dead animal parts" is true, but it sounds gross, like they found a dead carcass on the side of the road or something!