Oliver Smithies (born June 23 1925) is a British-born American geneticist and Nobel laureate, credited with the invention of gel electrophoresis in 1950, and the simultaneous discovery, with Mario Capecchi, of the technique of homologous recombination of transgenic DNA with genomic DNA, a much more reliable method of altering animal genomes than previously used, and the technique behind gene targeting and knockout mice.