Only 20 years ago, July 5, 1996, scientists cloned a sheep, Dolly. Now genetics have advanced to gene editing, a technique that is promising to pave the way for curing genetically carried illnesses, like certain cancers. But how does it all work? And what are the challenges?Only 20 years ago, July 5, 1996, scientists cloned a sheep, Dolly. Now genetics have advanced to gene editing, a technique that is promising to pave the way for curing genetically carried illnesses, like certain cancers. But how does it all work? And what are the challenges?