Some women carry mitochondrial defects that they can pass onto their babies. With mitochondrial donation, a little bit of genetic code is taken from a donor to ensure the baby won't have that defect. However, using the DNA from three people to make a baby is not legal in many places,
. (How will the child handle the fact that it came from three people, for example.) US doctors travelled to Mexico to carry out the September 2016 procedure, which seemed scandalous to some. The doctors, as well as other supporters in the medical community, heralded the achievement
. Learn more about the procedure in the video below.