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He Jiankui, associate professor at the Southern University of Science and Technology of China, listens during a panel discussion at the Second International Summit on Human Genome Editing in Hong Kong, China, on Wednesday, Nov. 28, 2018. He, the Chinese researcher who says he altered the genes of a pair of twin girls, stood by his work Wednesday and revealed a second pregnancy has resulted from the procedure amid growing condemnation of the controversial project. Photographer: Anthony Kwan/Bloomberg via Getty Images

He Jiankui, associate professor at the Southern University of Science and Technology of China, listens during a panel discussion at the Second International Summit on Human Genome Editing in Hong Kong, China, on Wednesday, Nov. 28, 2018. He, the Chinese researcher who says he altered the genes of a pair of twin girls, stood by his work Wednesday and revealed a second pregnancy has resulted from the procedure amid growing condemnation of the controversial project. Photographer: Anthony Kwan/Bloomberg via Getty Images

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He Jiankui, associate professor at the Southern University of Science and Technology of China, speaks at the Second International Summit on Human Genome Editing in Hong Kong, China, on Wednesday, Nov. 28, 2018. He, the Chinese researcher who says he altered the genes of a pair of twin girls, stood by his work Wednesday and revealed a second pregnancy has resulted from the procedure amid growing condemnation of the controversial project. Photographer: Anthony Kwan/Bloomberg via Getty Images

He Jiankui, associate professor at the Southern University of Science and Technology of China, speaks at the Second International Summit on Human Genome Editing in Hong Kong, China, on Wednesday, Nov. 28, 2018. He, the Chinese researcher who says he altered the genes of a pair of twin girls, stood by his work Wednesday and revealed a second pregnancy has resulted from the procedure amid growing condemnation of the controversial project. Photographer: Anthony Kwan/Bloomberg via Getty Images

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He Jiankui, associate professor at the Southern University of Science and Technology of China, speaks during a panel discussion at the Second International Summit on Human Genome Editing in Hong Kong, China, on Wednesday, Nov. 28, 2018. He, the Chinese researcher who says he altered the genes of a pair of twin girls, stood by his work Wednesday and revealed a second pregnancy has resulted from the procedure amid growing condemnation of the controversial project. Photographer: Anthony Kwan/Bloomberg via Getty Images

He Jiankui, associate professor at the Southern University of Science and Technology of China, speaks during a panel discussion at the Second International Summit on Human Genome Editing in Hong Kong, China, on Wednesday, Nov. 28, 2018. He, the Chinese researcher who says he altered the genes of a pair of twin girls, stood by his work Wednesday and revealed a second pregnancy has resulted from the procedure amid growing condemnation of the controversial project. Photographer: Anthony Kwan/Bloomberg via Getty Images

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He Jiankui, associate professor at the Southern University of Science and Technology of China, walks on stage to deliver a speech at the Second International Summit on Human Genome Editing in Hong Kong, China, on Wednesday, Nov. 28, 2018. He, the Chinese researcher who said he altered the genes of twin baby girls as embryos, said he has submitted the study to a scientific journal for review. Photographer: Anthony Kwan/Bloomberg via Getty Images

He Jiankui, associate professor at the Southern University of Science and Technology of China, walks on stage to deliver a speech at the Second International Summit on Human Genome Editing in Hong Kong, China, on Wednesday, Nov. 28, 2018. He, the Chinese researcher who said he altered the genes of twin baby girls as embryos, said he has submitted the study to a scientific journal for review. Photographer: Anthony Kwan/Bloomberg via Getty Images

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He Jiankui, associate professor at the Southern University of Science and Technology of China, speaks at the Second International Summit on Human Genome Editing in Hong Kong, China, on Wednesday, Nov. 28, 2018. He, the Chinese researcher who said he altered the genes of twin baby girls as embryos, said he has submitted the study to a scientific journal for review. Photographer: Anthony Kwan/Bloomberg via Getty Images

He Jiankui, associate professor at the Southern University of Science and Technology of China, speaks at the Second International Summit on Human Genome Editing in Hong Kong, China, on Wednesday, Nov. 28, 2018. He, the Chinese researcher who said he altered the genes of twin baby girls as embryos, said he has submitted the study to a scientific journal for review. Photographer: Anthony Kwan/Bloomberg via Getty Images