We should distinguish between ways our food can be genetically modified.
Nearly all our fruits and vegetables have been genetically altered over the centuries. Most of what we eat wasn't originally found that way in nature, it was originally intentionally changed in pre-modern times to be bigger, better tasting, longer shelf life, easier to grow and so on. The question is was this done naturally, such as hybridization - or unnaturally in a lab somewhere, using chemicals or parts from unrelated species.
10,000 years ago there was no such thing as corn. In Mesoamerica, a member of the grass family - with a single small kernel and tough hull - was genetically altered over what must have been generations to become the multi-kernelled maize the Spanish found there.