How do we do this with non GMO products? I'm eating today organic crops which were either never eaten by my previous generations, or didn't even exist then. Let's take a garden-style non GMO cherry tomatoes. They didn't even exist a few hundred years ago and didn't become popular until 20th century. In eastern europe I don't think I've ever seen one before late 90s.

So what's the difference between a genetic mixture like cherry tomatoes and GMO tomatoes? Why should I be more scared of long-term effect of one over the other?