Next, could GM foods cause allergies? Most allergies are caused by one of a small number of proteins.  Moreover, the amount of information available about what makes a protein allergenic has increase significantly in recent years, making it easier to check a protein for possible allergenicity. Each protein for which genetic instructions are being added must be analyzed for its potential to cause an allergy. And  if there is any indication that it could be an allergen  and even if the gene came from a plant, like a peanut plant, that produces a common allergen, it must be analyzed and tested for allergenicity.