It felt as if humanity had crossed an important line: In China, a scientist named He Jiankui announced recently that twins had been born in November with a gene that he had edited when they were embryos.But in some ways this news is not new at all. A few genetically modified people already walk among us.In the mid-1990s, fertility doctors in New Jersey got an idea for how to help women have children. They suspected that some women struggled to become pregnant because of defective material in their eggs.To rejuvenate them, the doctors drew off some of the jellylike filling in eggs donated by healthy women and injected it into the eggs of their patients before performing in vitro fertilization.
