British women could be receiving the treatment, called mitochondrial replacement thereapy (MRT), on the NHS as early as next spring.
It's after an independent panel of experts cleared away remaining safety hurdles to recommend "cautious adoption" of the method, which aims to stop inherited diseases.
The UK fertility regulator, the Human Fertilisation and Embryology Authority (HFEA), is now almost certain to give the final go-ahead for the treatments.
Supporters say the move could stop the suffering of thousands of people. The Church of England has opposed the move on safety grounds, while other Christians say a person should only be made of DNA from two people, as God intended.
Babies born after MRT would have three genetic parents. A tiny proportion of their DNA would come from their mother, father and a third person, an egg donor.
The aim is to replace abnormal genes in the mitochondria, rod-like power plants in cells that generate energy.
Mitochondria only hold around 0.1% of a person's DNA, which is always inherited from the mother and has no influence over individual characteristics such as appearance and personality.
Faulty mitochondrial DNA can cause potentially fatal conditions affecting vital organs, muscles, vision, growth and mental ability.
Dan Boucher, from the Christian charity CARE, told Premier: "We have major, major concerns about the impact of that in the longer term for our culture and what it means to be human. Once you begin to cross that threshold, what it means to be human changes."
"It opens the door of the commodification of people and people not just beings in themselves, but entities that can be designed.
"That has massive cultural consequences.
"This isn't going to cure anyone. It's about creating a new life that doesn't have mitochondrial disease, and the point can be made that the option is open to adopt, or indeed to have a donor egg, so there are other options."
Listen to Premier's Aaron James speaking to Dan Boucher:
