Pavlo Mazur, a clinic’s embryo scientist (top) inserts a needle into a fertilized egg (bottom left) to extract the DNA of a man and woman trying to have a baby. He then transfers the DNA into a fertilized egg from an egg donor that has had most of its DNA removed. That creates an embryo (bottom right) with DNA from three different people.

Pavlo Mazur, a clinic’s embryo scientist (top) inserts a needle into a fertilized egg (bottom left) to extract the DNA of a man and woman trying to have a baby. He then transfers the DNA into a fertilized egg from an egg donor that has had most of its DNA removed. That creates an embryo (bottom right) with DNA from three different people.