The United Kingdom could become the first country in the world to allow a scientific procedure that lets children be born with the DNA of three people.
Politicians there are holding their first debate on it today, and will vote on whether to legalize the technique in the coming months.
Scientists claim the procedure will eliminate debilitating genetic diseases, but it would also mean changing their human genetic code forever.
As the BBC's science correspondent Rebecca Morelle reports, a handful of people have already been born this way.
- Rebecca Morelle, global science correspondent for BBC News. She tweets @rebeccamorelle.
This segment aired on September 2, 2014.