Some foods do cause it though. It just depends upon the type of food you eat. There's an anatomical term used to why you don't gag when you eat but I don't remember its name. Perhaps others here will recall it and let us know what it is.
Because your brain relaxes it while you are eating, swallowing actually pulls the food away from the soft palate, so that it doesn't trigger the pharyngeal reflex. You can learn to relax your gag reflex, or stimulate your gag reflex. You just have to trick your brain into ignoring the signs that your nerves are sending.
The smell and look of porridge and whetobix make me gag or at least feel like it Please Register or Log in to view the hidden image!