James D. Watson, whose co-discovery of the twisted-ladder structure of DNA in 1953 helped light the long fuse on a revolution in medicine, crimefighting, genealogy and ethics, has died, according to his former research lab.

James Watson — the Nobel laureate co-credited with the pivotal discovery of DNA's double-helix structure, but whose career was later tainted by his repeated racist remarks — has died, his former lab s...