However both the donkey and the horse got to where they are by human breeding.GMOs are different.Here is the difference.
When a donkey and horse are interbred the offspring, the mule, is sterile. These are two different spieces and something does not want this mix to continue.
Corn was originally teocinte. Modern corn can not breed with teocinte, doesn't mean that we didn't talk it all the way down that path.
Many of our high yield crops are hybrids, some are even sterile.