The World is full of drugs, some of which are good and some of which are bad. What they all have in common is that they create addiction (a craving for more).
One of the first drugs you get exposed to in your life is the casomorphine in breast milk. This is a very useful drug that helps stimulate the mother-infant bond and helps secure that the infant gets all the nutrients it needs. It also exists in cow’s milk, and thus in all the dairy products we consume. It gets very concentrated in cheese, which helps explain why cheese is one of my favorite foods.