A public consultation has been launched to discuss the ethics of using three people to create one baby.
The technique could be used to prevent debilitating and fatal mitochondrial diseases, which are passed down only from mother to child.
However, the resulting baby would contain genetic information from three people - two parents and a donor woman.
Ministers could change the law to make the technique legal after the results of the consultation are known.
About one in 200 children are born with faulty mitochondria - the tiny power stations which provide energy to every cell in the body.
Most show little or no symptoms, but in the severest cases the cells of the body are starved of energy. It can lead to muscle weakness, blindness, heart failure and in some cases can be fatal.
Mitochondria are passed on from the mother's egg to the child - the father does not pass on mitochondria through his sperm. The idea to prevent this is to add a healthy woman's mitochondria into the mix.
Two main techniques have been shown to work in the laboratory, by using a donor embryo or a donor egg.
