Some very cautious people believe that genetically modified foods will change our DNA. Crops can mutate as a result of cross contamination but whether that would extend to humans is very doubtful.
These foods are also known as biotech foods, or crap, depending on your viewpoint. However, most of the concerns are related to the intellectual property of the food. Nobody, except the Biotech companies would want any company monopolising our food.
Many small companies are really suffering at the moment due to the lack of proper investment. Some have turned to Company Voluntary Arrangements in order to survive when a winding up petition arrives out of the blue.