Rebecca Morelle examines how children could be born with DNA from three people. The UK has just become the first country in the world to make this legal.

Alana Saarinen is a thirteen year old girl who lives with her mum and dad in Michigan, USA. She loves playing golf and the piano, listening to music and hanging out with friends. In those respects, she's like many teenagers around the world. Except she's not, because every cell in Alana's body isn't like mine and yours; Alana is one of a handful of people in the world who have DNA from three people.

The BBC's Science Correspondent Rebecca Morelle explores how more children like Alana could be born.

This programme examines the safety and health implications of this new science. For some it is controversial. For those who have these specific genetic diseases, it is the way they could have their own healthy child. The UK is playing a pioneering role in developing the technique, called mitochondrial replacement, and Parliament has just voted to make the process legal.

But despite that, there are a small number of children in the world, like Alana Saarinen, who have DNA from three people already. Although a small sample, they could answer some of the questions people have, such as will they be healthy, do they feel like they have three parents and would they like to trace the donor one day in the future?

Producer: Charlotte Pritchard.