Gene editing probably won’t make the next Spiderman, but it’s possible that the world’s first gene-edited babies have been born. He Jiankui, a Chinese scientist, shocked the world and its ethical sensibilities by revealing last week that he used CRISPR to lower two twin girls’ risk of HIV infection. And a third baby is on the way. Less HIV is certainly something we can all get behind, especially when World AIDS Day was last week. But CRISPR is still brand-spanking new, and scientists are questioning the medical appropriateness of this use of gene editing when the consequences aren’t super well understood and possibly catastrophic. Even a CRISPR co-founder is calling for a moratorium on live-embryo testing. Is this a breakthrough like the first IVF birth, or a slippery slope? From Nature: six questions that remain.