A recently completed meta analysis of 6000 different peer reviewed scientific studies conducted over the last 21 years from all over the world show that GMO corn is higher yield and less toxic than non-GMO varieties:
https://www.sciencealert.com/after-t...y-good-for-you
https://www.nature.com/articles/s41598-018-21284-2
Grandpa was a big advocate from the 1950s right up to the day he died. Looks like science supports his position.