Without being too graphic, check your stool after eating a couple ears of corn. You will see whole kernels that survived intact.
Corn is not wheat. However, like the wheat, it is not eaten raw and must also pass thru the stomach.
You are seeing a cellulose shell on the corn after the (cooked/processed) corn kernel has passed thru the GI tract and what can be digested has been. That corn is also likely GMO and that still does not answer the question:”By what mechanism does the digested portion of the cooked and processed corn (wheat) affect human gene function?”
Cow patties also contain the remains of corn that were not digested. Cows still survive on it. So do chickens.
Examining one’s stool says nothing about plant genes affecting human genes with regard to the plant’s processing into food and further processing within the body.