The definition of a GMO is a genetically modified organism. You mostly hear about this in GMO seeds, which is a big controversy among farmers. I am assuming you are pro for all GMOs (correct me if i'm wrong) but i will mostly be focusing on GMO seeds because that is the main purpose of even using GMO. Using these seeds have many harmful effects on the environment and pollute the soil, therefore i don't think they should be used. What you gain does not outweigh the harmful side effects.