My allergies

It is hard to know how to teach Isaac about his allergies. For the most part if he has had a bad experience with the offending food he knows first hand that that particular food doesn't bode well with his system. So he often he'll say - I don't like fish, or I don't like peanuts. As a two year old - he even knows that his food allergies are the cause of him disliking food. So why am I surprised that Eli has adopted the "I have food allergies" response to any food he dislikes. Eli asked yesterday what we were having for dinner and I said - chicken casserole. "Hum," he said, "I am pretty sure I am allergic to that - can I have pizza instead?"