Separate but Equal

A common mistake is that people think that if the thing they're allergic to isn't an ingredient in their food, they won't have a reaction. But sometimes if it's in the same box as the thing they're allergic to, they can still have a reaction.
One time my aunt put cookies that had nuts in them in the same box as a cookie that I ate (that didn't have nuts), and I had a reaction. 
This is why it's important to keep the foods separate but equal. You can still have your delicious food, but without it touching the things you're allergic to.