BOSTON — You’ve heard the advice: For clean hands, scrub with soap and water for as long as it takes to sing “Happy Birthday” twice. But is hand sanitizer just squirt and go? Finally, there’s a scientific answer: To kill bacteria, rub for at least 15 to 30 seconds. After 45 seconds, you’re not doing […]

Scientists have found a clue to why one type of DNA is passed down to children by their mothers — but not their fathers. DNA inside energy-producing organelles called mitochondria is destroyed in a dad’s sperm shortly after it fertilizes an egg, researchers report online June 23 in Science. A protein called CPS-6 cuts apart […]