It is true that since GMOs were introduced in the 1980s, people in the U.S. have consumed a lot more of them. By one estimate, 70 percent of processed foods in the U.S. contain genetically modified ingredients [source: Scientific American].
But that's largely because a few big-ticket crops — corn, in particular— are used in a lot of foods. According to one anti-GMO Web site, there are around 60 GMOs that have been approved in the U.S. for human consumption or animal feed. That list includes 20 varieties of corn, 11 varieties of oilseed rape/canola, 11 varieties of cotton, six tomato varieties, three types of soybeans and sugar beets, two different squash varieties, and single types of cantaloupe, rice, flax, radicchio, papaya, alfalfa and wheat [source: Organic Consumers].
But of all those crops, only corn, soybeans, cotton, canola, squash, and papaya grown in Hawaii currently are being commercially cultivated. Some were tried but eventually taken off the market, while others — like wheat and rice—have never been grown in the U.S. [source: Organic Consumers]. The upshot is that most of the vegetables and fruits in your local supermarket are non-GMOs.
One big reason GMOs haven't caught on even more extensively is that U.S. consumers are suspicious of them. According to a June 2013 ABC News poll, 52 percent of Americans believe such foods are unsafe [source: Langer].