Should we allow babies to be created from three people?
The House of Lords will vote on Tuesday on whether to allow the creation of babies with DNA from three people.
The fertility technique aims to help women at risk of passing on serious and often life-threatening genetic diseases through their DNA.
Britain would be the first country to legalise the procedure and it is estimated it could help around 150 couples a year.
The problem occurs when a woman carries defective DNA in a microscopic part of their cells called mitochondria.
Although only a tiny fraction of the DNA passed down to a child comes from the mitochondria, it can be enough to produce deadly disease.
The technique under debate allows scientists to replace this specific DNA with genetic material from a donor woman with properly functioning mitochondria.
The first attempt is expected this year, if there is a Yes vote. However, many people oppose the technology on ethical grounds.
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