Jeffreys Reads a Blurred X-Ray and Invents Genetic Fingerprinting

Forensic genetics analyses DNA to establish or exclude identity, ancestry and biological relationship, applying a statistical genetic match rather than relying on circumstantial or documentary evidence alone. The British geneticist Alec Jeffreys developed the technique at the University of Leicester and, in 1985, first demonstrated what he named DNA fingerprinting, using variable regions of the genome to show that no two individuals other than identical twins carry the same pattern, a discovery he made while examining an X-ray image of a DNA sample and immediately recognized as usable for identification.

A relic claimed as a saint's bone, a lineage claimed to descend from a religious founder, or a set of remains claimed to belong to a specific historical figure can each now be tested directly against Jeffreys's method rather than assessed only on the strength of the tradition that names them. The atlas relies on forensic genetics wherever a claim of biological identity or descent is testable, reporting what a genetic result does or does not establish, distinct from what a tradition asserts on documentary or oral grounds alone. Jeffreys's technique also settles the negative case cleanly, showing that two claimed relics or lineages are unrelated, which a documentary record alone can rarely establish with the same certainty.