IT USED to be so simple. Girl met boy. Gametes were transferred through plumbing optimised by millions of years of evolution. Then, nine months later, part of that plumbing presented the finished product to the world. Now things are becoming a lot more complicated. A report published on February 14th by America's National Academy of Sciences gives qualified support to research into gene-editing techniques so precise that genetic diseases like haemophilia and sickle-cell anaemia can be fixed before an embryo even starts to develop. The idea of human cloning triggered a furore when, 20 years ago this week, Dolly the sheep was revealed to the world (see pages 17-20); much fuss about nothing, some would say, looking back. But other technological advances are making cloning humans steadily more feasible.
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