Leave this field empty if you're human: In 2015, an impactful study found that sweet potatoes are naturally transgenic — they’ve been GM’d by Agrobacterium. This came as a surprise for many consumers, but many biologists suspected that sweet potatoes weren’t that unique, and several other plants went through a similar process. Tatiana Matveeva and Léon Otten studied the genomes of some 356 dicot species and found 15 naturally occurring transgenic species. ADVERTISEMENT It’s still a rare occurrence, but 1 in 20 is too much to just chalk it up to a freak accident. “This particular type of horizontal gene transfer (HGT) could play a role in plant evolution,” the researchers say.