The GMO thing makes me bang my head on the desk. The dangers of GMO's has been blown completely out of proportion.
As to your Aunt or people with criticisms... kill them with humor. It's not even worth it to try to use logic. You are putting yourself in danger by smoking. Any person who doesn't know this by now is an idiot or completely from a deserted island. Trying to argue away the dangers is even more stupid. But... everything has a risk. Try the joke thing. If they can't take a joke, punch them in the face. YMMV