Manufacturers of genetically modified crops make great claims about them especially when lobbying government, but they do not explain the disadvantages about their products.
Take, for example, crops genetically engineered maize which rather cleverly produces insecticidal poisons derived from the bacterium bacillus thuringiensis to kill pest which can wipe out a crop of maize. If your GM seed maize has its own built in insecticide, you do not need to smother your maize with conventional insecticides but should be able to rely on the GM maize to kill those pests. .
Bacillus thuringiensis should kill western corn rootworm, which is a serious pest of maize. However, it does not always do this, because the clever pests can mutate and the GM maize does not release enough poison to kill the rootworm.
Man proposes and nature disposes.