He Jiankui, the Chinese biophysicist whose controversial2018 experiment led to the birth of three gene-edited children, says he’s returned to work on the concept of altering the DNA of people at conception, but with a difference. 

This time around, he says, he will restrict his research to animals and nonviable human embryos. He will not try to create a pregnancy, at least until society comes to accept his vision for “genetic vaccines” against common diseases.