My print column examines the math of DNA-based identity testing, in light of the technique's use by the U.S. to confirm the identity of the body believed to be Osama bin Laden's. Though a government official said that an initial test showed with 99.9% certainty that bin Laden had been killed, and later tests were "absolutely conclusive," not all details have been released, including whose genetic material was used for comparison. ABC News reported that investigators had subpoenaed a DNA sample from Massachusetts General Hospital in Boston, where a sister of bin Laden's had died of cancer. But a spokesman...