Most foods in the grocery stores that we buy are genetically modified. About 90 percent of the country's soy and corn crops are genetically modified. Since almost all processed foods contain their by-products—and corn, the nation's largest crop, is a staple for animal feed—chances are high that you are eating genetically modified foods. How can you tell? For now, there are no labels required as there are in countries like Britain. Look for ingredients like maltodextrin, high fructose corn syrup , dextrose, soy lecithin, and corn starch. And unless your meat is grass-fed and specifically GMO-free, it's likely to have been affected, too.