One of the issues with GMO foods is that we don't actually know for a fact exactly how the changes we make in them work, or what effect they may have in the human body over long periods of time. We just don't know.
EDIT: I will grant that all of these studies deal with animals rather than directly at effects on humans, but it doesn't seem there is compelling evidence thus far for one to assume there would be a significant difference.
[0] http://www.fass.org/page.asp?pageID=52&autotry=true&ULnotkn=...
In 100 years people may reasonably feel that pre 2060's GMO food is fine, but that new stuff is risky. And they would be reasonable to feel that way. After all, we have recalled a lot of great new products from the market due to long term issues.
PS: This might be unreasonable, however the pro GMO argument is lower food costs which is a non issue for many people.
Changes are changes, whether random or induced mutation. I feel better if there's at least one brain inspecting the changes vs throwing dice.
Random or induced mutation like they do in GMO has lots of unintended consequences(for example radiating it). It is like a program that has not been debugged, only that a crash could be people dying or getting ill in the thousands or millions.
Also mixing genes from species that have nothing to do with each other like creatures that live in deep ocean that emit light with those that live on the surface will also have unintended consequences.
Human beings could be cocky and arrogant. I have a river near my house. Someone had the brilliant idea of introducing an alien small fish to help native fish as food. The unintended consequence was that the new small fish ate the eggs of native fish and made them disappear completely from the river.
And why do you think that genetic code within the same species is different in the first place...?
Is it really intellectually dishonest, or did someone else just come up with a different risk and cost/benefit analysis from yours? I'm not saying they're right, but it's entirely possible they're making an honest mistake. (Also, the ethics of science get tricky when your subjects are human beings.)
Exceptions can of course be made for places that are experiencing acute malnutrition, but even so it probably makes much more sense using the same money to make sure the African farmers have access to fertilizer so they can get better yields.
I mean, if you come across a dish of quinoa, macadamia nuts, and beef, would you object to eating it because it contains DNAs that never made contact with each other for a hundred million years, and there's just no guarantee what their combined power could do once ingested?
The only credible potential danger of GMO food is what they might do to the ecosystem while they're still alive (that is, before you eat them), but somehow most GMO opponents just gloss over this important distinction.