By Alice Park
In November 2018, Chinese biophysicist Jiankui He stunned the world when he announced that he had used a controversial gene-editing technology, called CRISPR, to genetically alter the genes in embryos and give them immunity to HIV. The embryos were transferred to the woman who provided the eggs to create them, and twin girls were born.
The move, considered highly experimental and unethical by most scientists around the world, prompted intense debate in the scientific community about not just the implications for the twins, but for society as well. When applied to human eggs, sperm and embryos, gene-editing technologies, of which CRISPR is the most precise, can alter the genes that people pass on to the next generation, and therefore modify the gene pool of the human species.