For related articles and more information, please visit OCA’s Genetic Engineering page and our Millions Against Monsanto page.

By now, you’ve likely heard about genetically modified organisms (GMOs) and the controversy over whether they’re the answer to world hunger or the devil incarnate. But for right now, let’s leave aside that debate and turn to a more basic question: When you go to the supermarket, do you know which foods are most likely to be-or contain ingredients that are-genetically engineered? A handy FAQ:

So what exactly are genetically modified organisms? GMOs are plants or animals that have undergone a process wherein scientists alter their genes with DNA from different species of living organisms, bacteria, or viruses to get desired traits such as resistance to disease or tolerance of pesticides.

But haven’t farmers been selectively breeding crops to get larger harvests for centuries? How is this any different? Over at Grist, Nathanael Johnson has a great answer to this question-but in a nutshell: Yes, farmers throughout history have been raising their plants to achieve certain desired traits such as improved taste, yield, or disease resistance. But this kind of breeding still relies on the natural reproductive processes of the organisms, where as genetic engineering involves the addition of foreign genes that would not occur in nature.

Am I eating GMOs? Probably. Since several common ingredients like corn starch and soy protein are predominantly derived from genetically modified crops, it’s pretty hard to avoid GM foods altogether. In fact, GMOs are present in 60 to 70 percent of foods on US supermarket shelves, according to Bill Freese at the Center for Food Safety; the vast majority of processed foods contain GMOs. One major exception is fresh fruits and veggies. The only GM produce you’re likely to find is the Hawaiian papaya, a small amount of zucchini and squash, and some sweet corn. No meat, fish, and poultry products approved for direct human consumption are bioengineered at this point, though most of the feed for livestock and fish is derived from GM corn, alfalfa, and other biotech grains. Only organic varieties of these animal products are guaranteed GMO-free feed.