DNA for lying

My saga continues. I found a sugar daddy lollipop eaten (if was being saved for Jason, but not in am.) I asked boys who ate it. They both denied it. Well, I know I didn't eat it so one of them had to. I said then I am going to take the stick and wrapper and get some DNA testing done on it. They curiously asked what that was. I explained that by the saliva on the stick they could determine who had eaten it. I also told them it was very expensive and that I would have to sell the person who lied's DS lit or DSi. I said I was going to give them 60 seconds to tell me the truth. Well, Jason fessed up. He had eaten the lollipop. When I told him he was grounded, he said, "since when is lying something we get punished for?" Huh? Has he been living with me for 11 years? Have I really let lying slide? I have so much work to do with these two.
AHHHHHH!!!!!
-Becky