[vissin]

Well, every single genus, species, individual is characterized by it's genetic makeup. We all know very well now that it's our genes that determine every aspect of our nature. And we also know the chemical composition of genes (Remember the helical structure that you read about in high school?)

Now what if we take an organic subject and slightly alter it's genetic makeup. This way we should be able to alter it's nature. This is what's called genetic engineering. Examples would be a philanthropist inclined on eradicating world hunger trying to alter the genetic makeup of potatoes to make it grow bigger in size or a military organization trying to create the ultimate super soldier (Like Goblin from the Spiderman Movie).

Hope this is of help.