Autoradiograph of gel obtained by Southern blot of the first genetic fingerprint, prepared by Alec Jeffreys on 19th September, 1984 (see note)

Apart from identical twins, everybody’s DNA has a characteristic pattern. Certain regions of DNA are particularly variable. This is an autoradiograph of the first DNA fingerprint, prepared by Alec Jeffreys on 19 September 1984. Sir Alec Jeffreys (b. 1950) is an English geneticist who discovered genetic fingerprinting almost by accident. It has now become an invaluable police tool, identifying criminals from blood, skin or saliva left at crime scenes. This example is an X-ray of the original, which is too fragile to display.