There are a lot of misperceptions about genetically modified organisms (or G.M.O.s.) The white button mushroom, for instance, has had its DNA tweaked in a laboratory to create a version that doesn’t brown as quickly after being sliced. But it’s not a G.M.O. as is widely believed.
A G.M.O. is a plant or an animal whose DNA was altered in a laboratory by injecting foreign DNA—that is, DNA from another organism.
Similarly, those cube-shaped watermelons haven’t had their DNA messed with. They’re simply, grown in a box.