Genetic Engineering, the process of extracting DNA (deoxyribonucleic acid, which makes up the genes of all living things) from one organism and combining it with the DNA of another organism, thus introducing new hereditary traits into the recipient organism. The nature and characteristics of every living creature is determined by the special combinations of genes carried by its cells. The slightest alteration in these combinations can bring about significant changes in an organism and also its progeny. The science of devising techniques of modifying or controlling genes and genetic combinations is referred to as genetic engineering. It was practiced in one form or another in the past by farmers and agriculturists trying to create economically viable species of plants and animals through various breeding techniques Genetic engineering, as a science, was developed in the mid-1970's primarily to create new strains of microorganisms that produce certain chemicals useful in manufacturing or as drugs. Genetic engineering is now also applied to improving plants and creating transgenic animals (animals containing foreign genetic material).

Some persons oppose genetic engineering on religious, ethical, or social grounds. Among the religious questions is whether humans have the right to transfer traits from one organism to another. A social concern is the possibility of creating harmful organisms that, if accidentally released into the environment, could cause epidemics.The creation of human clones, for example, is facing serious opposition especially on moral grounds. Organizations, such as the National Institutes of Health (NIH), are seeking to control the harmful effects of genetic engineering by imposing guidelines and safety measures for genetic experimentation. Treatment of hereditary defects through gene transplantation and controlled interchange of genes between specified species was approved in 1985 and 1987 respectively by the NIH and the National Academy of Sciences. The USDA has framed regulations for the genetic alteration of plants by plant breeders.

The U.S. Supreme Court ruled in 1980 that genetically engineered microorganisms could be patented. In 1988 the U.S. Patent and Trademark Office issued its first patent for a higher form of life, a transgenic mouse that is highly susceptible to certain cancers that appear frequently in humans. This mouse is used in cancer research.