When I hear the anti-GMO and anti-evolution kooks talk, I look at my hands.
Talking about "foreign" genes is nonsense. We share many, many genes with animals. Limbs, for example, take many forms in their derived state, but the genes that are behind 4-limbedness go back a looong way.
Same with the genes for sight (light recognition).
Now, according to a report in the New York Times, scientists have identified the ur-gene that accounts for multicellularity.
That's really far back, maybe 800 million years.
Not only that, but they re-created the original version of the gene evolved by unicellular creatures. And they determined that it evolved by a single site mutation from a gene that had another function entirely.
You don't really understand something until you can take it apart and mix up the parts and put it back together.