Marcy Darnovsky, director of the Center for Genetics and Society in Berkeley, California, says that the approach would also avoid many of the concerns posed by the concept of three-parent embryos, which her group opposes. But she remains sceptical that these methods will make it into the clinic any time soon, as creating a healthy child is not the same as curing a disease — and therefore may be outweighed by the risks. And in the strictest sense, she adds, mitochondrial editing still creates modifications in the germline.