I Eat Mutants!
I'm on a roll today. Rather sick of watching so much energy devoted to ridiculous battles. And yes, GMFs aren't technically mutants, they're recombinants.
Everybody and their dog in the USA is concerned about eating genetically altered produce. May I take this moment to say YOU'RE BEING STUPID. Do Americans not take biology in high school? Does the media think it's funny to spread disinformation? How about a quick simple lesson, shall we?
This is how your body works. We all know the stomach is acidic, right? The acid activates digestive enzymes (proteins that help a reaction to take place) and breaks down the food you eat. Enzymes are at work everywhere in your digestive tract, from your mouth to your intestines. One of those enzymes operating in your small intestine is called "nuclease".
Genetic material (nucleic stuff - DNA, RNA, acids...) is made up of nitrogenous bases, sugars, phosphates, which are all useable by your body to build your own cells. In various combinations, the nitrogen bases, sugars, and phosphates make up five nucleic bases - four are used as building blocks for DNA, the fifth in RNA. That's all your DNA is made up of - these building blocks, which will determine everything about you depending on their order in your cells.
Now, when you eat genetic material, nuclease breaks it down into it's five building blocks. (Other enzymes break it down into it's three major ingredients, but that's unnecessary for now.) Your body takes up the material and uses it. It doesn't matter what it came from, what the DNA was encoded to do, or even whether or not you consumed cancerous cells. The DNA is torn apart in your mouth and stomach, stripped down to it's parts in the intestine and absorbed. The order of those parts doesn't matter, it's all the same thing once your body has broken it down to get it through the intestinal wall.
What genetic engineering does is change the order of the DNA in an organism to produce certain qualities in it. So one could give a plant a gene (DNA chunk) to encourage larger storage of food, making it more attractive as a source of nutrients. One can't alter the plants excessively - the plants still needs to live and be able to function as a plant. At most we can tweak the plant's lifestyle a little bit and still have a viable result. If your stomach is mixing up DNA anyways, it doesn't matter in the slightest if we mix the DNA up a little in the plant before you eat it. We've attemped to do silly like turn all plants into legumes (who have little buddies on their roots to take nitrogen out of the soil for them) - and we haven't been successful because most plants can't support the little guys on their roots. We can't play God with our food. We can only help it along, make it a better investment. This doesn't harm the human body in any way - even if your carrot was given the DNA telling it to grow horns and and a set of gills.
The only drawback I can see to genetic modification of food is that it is conceivable to produce a plant that some people would have an allergic reaction to. In which case you get the peanut scenario - manufacturers will be required to state the content or modification to the foodstuff to prevent horrible things happening. Ecologically, I don't think that we ought to just let GMFs out into nature, because there is some potential for harm to the system. (Note that GMFs differ from monoculture, which is when farmers plant seeds of the same genetic code for convenience, but don't introduce anything "new" into the ecosystem.) Carefully controlled greenhousing is an option - we could potentially meet all of our food requirements with greenhousing - so it would be more like a lab product than an agricultural product, ideally. Considering that there are at least 3 billion too many people on the planet, we may need to turn to GMFs out of necessity instead of luxury or vanity. In which case, it's a good idea for Mr. Joe Public to get over it.