DNA fingerprinting Method of isolating and visualizing of sequences of DNA developed in 1984 by Alec Jeffreys. He noticed the existence of minisatellites that do not contribute to the function of a gene but are repeated within the gene and in other genes of a DNA sample. Jeffreys also determined that each organism has a unique pattern of these minisatellites, the only exception being multiple individuals from a single zygote. This unique pattern of DNA fragments is revealed by Southern hybridization or by the polymerase chain reaction.