Artificial insertion of genes through Genetic Engineering yields unpredictable results
(Excerpt from: "Assessing the safety and nutritional quality of genetically engineered foods" by John Fagan. The heading above was created by the editor of this website)
Genetic engineering can create dangerous foods by generating mutations in the DNA of the food-producing organism. Inserting a recombinant gene into the DNA of a food-producing organism disrupts the natural sequence of genetic information within that DNA. Thus, the process of genetic engineering causes mutations to the food-producing organism. These mutations are a source of potential damaging effects of genetic engineering.
The location at which these mutations occur will be random, because genetic engineers cannot, by and large, control the site at which a recombinant gene is inserted into the DNA of the organism. They can cut and splice genes in the test tube with considerable precision, but the process of inserting those recombinant genes into the host is very imprecise.