Using Crispr, he tweaked the genes of three human embryos in an attempt to make them immune to HIV and used the embryos to start pregnancies. Scientists said the technology was too new to be used for human reproduction and that the DNA change amounted to genetic enhancement. A scientist who pioneered a technique to make embryos using DNA from three people is also involved. As Tie sees it, that challenge is to make the idea of human embryo editing more acceptable in society. The idea of editing human embryos is tantalizing, because any changes made to the reproductive cells are heritable.