From the early beginnings in the 1970's, however, it has now become possible to manipulate specific genes at a molecular level, using laboratory procedures on material taken from living organisms, which can be replaced in the organism, or put into a different one. It can be likened to taking a long, thin garment with a constantly varying pattern along its length, snipping out a section of pattern (an individual gene), modifying it and putting it back, or putting in a section with a different pattern (gene) taken from another garment.

In principle, this ought to be much more specific than selective breeding, but the uptake of the relevant modified gene is often quite low, particularly in animals. It also allows the creation of "transgenic" organisms, where a short section of genetic material from an unrelated species can be introduced into another (N.B. a transgenic animal does not mean a 50-50 mixture!).

Catherine Baker