LONDON — On July 17, the United Kingdom’s influential Nuffield Council on Bioethics implicitly endorsed “heritable genome editing”, declaring the practice of altering the DNA of a human embryo “morally permissible” under certain circumstances.

As the Ebola virus grips an unprecedentedly wide swathe of Africa, many are asking whether it is time to begin administering untested drugs and vaccines. Given that the disease can kill up to 90 per cent of its victims — higher than the mortality rate from the bubonic plag