This is a good forum on seeds: Seed Breeding
It looks like "if" the seeds had been modified its been bred out at this point. It also looks like the early 1900's they started modifying and that this is nothing new.
Hmmm! Checked out the site you posted with no reference to Sunflower seeds
When they mentioned corn being crossed with Agent Orange is why My wife ,daughters are not permit to purchase any thing from South East Asia. Especially Vietnam, Cambodia, Thailand, no matter how cheap the food is. Why are we in the first place even buying any thing from these countries? You can bet the President and all other politician's don't eat from these countries.
Just think we do this and rope are farmers and common workers because it's cheaper. Like to hell with the American's lives.