Edward backs up the conversation a bit, looking at his homunculus alternte. "How does being around us not affect you?" he asks. "Because those limbs should. The body piece of Mom we have came from another world and it works on every Sloth we've had come through that gave us reason to use it, and that body piece of Envy we used on your Envy was most certainly not from your world, so ... I would think body parts from us would affect you."