Paleontologists have found clear evidence of humans engaging in genetic modification of plants and animals since longer than there has been writing. If your grandfather was one of the first to dabble in creating GMOs, he must have known Noah personally, if not Adam ha-Rishon himself.
All that happened in the last cenutry was an improvement in technique. No reputable scientist claims GMOs have been proven to be “bad” – however in many countries (particulary in Europe) they have a rule that something must be proven to be “safe” (though in all fairness, the rule is designed primarily to protect inefficient farmers against competition from farmers in American and Britain using modern methods) . GMOs even if the definition is defined to the newer methods of accomplishing it are widely used, and are a major reason why people have enough to eat.
Without GMOs people would be starving in the streets. And if you really believe that falling birth rates are caused by GMOs, you are incredibly naive.