Rumors that scientists had edited the genomes of human embryos sparked controversy last month, and now, Chinese scientists have confirmed: it's true.

Genetically changing embryos, or germline modification, has been a hot topic of debate as many believe it to be unethical. The scientists responsible for conducting the controversial experiment - Junjiu Huang's team at Sun Yat-sen University in Guangzhou - believe that editing embryonic DNA could remove and replace genes responsible for causing devastating genetic diseases before the baby is born.

Those opposed to germline modification are worried that the technology could also be used as a means to unethical ends. In addition, the test had very unreliable results - only a small number of the injected embryos were successfully spliced and edited, while the DNA of some embryos had unintended mutations. Huang's paper on his findings were rejected by the prestigious journals Nature and Science in part because the editors had reservations about its ethical merit.