Up till now, all babies have had two genetic parents. That could soon change. Klöpper & Eisenschmidt GbR/iStockphoto hide caption

itoggle caption Klöpper & Eisenschmidt GbR/iStockphoto

Dennis Aabo Sorensen tests a prosthetic arm with sensory feedback in a laboratory in Rome in March 2013. Patrizia Tocci/Lifehand 2 hide caption

itoggle caption Patrizia Tocci/Lifehand 2

Smoking can mess up your looks, according to an ad campaign aimed at keeping teens from smoking. Courtesy of U.S. Food and Drug Administration hide caption

itoggle caption Courtesy of U.S. Food and Drug Administration

Playing outside can help kids — and their parents — maintain a healthy weight. iStockphoto hide caption

itoggle caption iStockphoto

You tried burping. You tried bouncing. You tried swaddling. Now what? iStockphoto hide caption

itoggle caption iStockphoto

He's not just getting a cold. He's building his microbiome. iStockphoto.com hide caption

itoggle caption iStockphoto.com

Say hello to your microbiome, Rob Stein. Our intrepid correspondent decided to get his gut bacteria analyzed. Now he's wondering if he needs to eat more garlic and onions. Morgan Walker/NPR hide caption

itoggle caption Morgan Walker/NPR

Hydrocodone, sold as Vicodin and other brand names, may face tighter restrictions on prescribing and use. Toby Talbot/AP hide caption

itoggle caption Toby Talbot/AP

This micrograph shows a single mitochondrion (yellow), one of many little energy factories inside a cell. Keith R. Porter/Science Source hide caption

itoggle caption Keith R. Porter/Science Source

Knight (left) and Bucheli take soil samples from beneath one of the decomposing bodies. Katie Hayes Luke for NPR hide caption

itoggle caption Katie Hayes Luke for NPR