Monsanto and others produce seeds that supposedly do not reproduce on their own. It is a bit like crossing a horse with a donkey to produce mules. The mules are sterile. Seed manufacturer do this for several reasons. But the biggest reason is profit motive. They want to force the farmer to buy the seeds from them every year. That said, mankind has been genetically modifying crops for thousands of years. they replanted the seeds from crops they liked and discarded plants that did not do well in their climate.