For decades, the debate on human gene-editing has identified and agreed upon certain limits that draw the line between ethical and unethical territory: for example, applications for diseases are accepted, but not for enhancements. However, society keeps pushing the limits, as seen with the advent of CRISPR technology and the birth of the first genetically modified babies in China. John H. Evans rethinks how we discuss and debate these collective limits, which havelong been characterized as a slippery slope. He examines past, present, and future arguments, and argues which limits can hold and which cannot, before we reach the dystopian bottom.