The method, pioneered by UK scientists, combines the egg and sperm from a mum and dad with a second egg from a donor woman. Children born through the three-person technique inherit most of their DNA, their genetic blueprint, from their parents, but also get a tiny amount, about 0.1%, from the second woman. This is a change that is passed down the generations. About one in 5,000 babies are born with mitochondrial disease. The team in Newcastle anticipate there is demand for 20 to 30 babies born through the three-person method each year. Some parents have faced the agony of...