It is because Bt cotton is a genetic modification and not a hybrid that is worrying. The difference has to be understood as many mistake both to mean the same thing. A hybrid is made when a farmer selects what he thinks are the two best plants he has of the same or closely-related species, and cross-pollinates them in order to obtain an even better plant that has the best characteristics of both the 'parents'. The genes of both parents are passed onto the "offspring" plant. While the farmer does indeed select the individual plants for crossing, nature does the rest and most of the work.

The hybrid may or may not be as good as or better than the parent plants depending on what qualities the farmer is looking for, but the experience of over 10,000 years has been that the plants are always healthy and strong. This is partly because the farmer tries to imitate nature in the wild by crossing plants from different fields instead of from the same row. The wind, insects and other wildlife carry plant reproductive material all over the place. There's no knowing which one crosses with which. But the resultant plants end up in mind-boggling diversity and evolve to adapt to the micro-climate, soil and water quality, temperature, and other factors prevailing in the spot where the new plant takes up residence.

Genetically modified organisms (GMOs) including plants make a compete departure from this safe, long and tested sustainable approach. In this case, man intervenes by altering the DNA structure of the plant by artificially introducing a gene cell from another organism which may not necessarily be a plant. It may be from an insect, animal, bird, fish, worm, virus, bacteria or any other organism. In other words, it can jump the species barrier. The alien gene is introduced from a completely different species that would have been impossible in nature. - Which is why opponents of genetically modified crops raise the point that if nature had meant for such interaction between totally unrelated species to occur, it would have happened long ago in the billions of years that Nature has been around.

Instead, Nature has kept unrelated species apart, and let each one be unique and have its own role in the global environment. Scientists forget that the nature of biological organisms is completely different from that of machines. The former are living things that go through continuous cycles of growth, reproduction and death for which they need no help from Man.

 Machines are not. They are clones of a man-made device made of identical components, each one having to be manufactured from scratch to finish. Yet misguided scientists expect exactly the same results each time from genetically modified plants. But living organisms have a life of their own. They keep evolving, and in their built-in drive to survive, the changes in them can bring about unintended consequences such as the outcome of unwanted plants that displace desired ones. This has already happened.