Genetically modified foods may be associated with allergies, immune problems, faulty insulin regulation, and other health problems---the bottom line is, we don't really know for sure. The long term effects aren't fully understood. In addition, many GMO crops are designed to resist herbicides and pests, so they are loaded with toxic residues. Wouldn't you like to know whether a food contains GMOs, so you make a choice of whether to eat it or not?