One in ten couples are infertile; a test tube baby is a possible answer for them.
Research with embryos can also provide clues to serious genetic disease and a greater understanding of why one in five pregnancies miscarries.
But is it morally acceptable to interfere with the process of nature? Should society be concerned at what might become routine genetic manipulation?
Margaret Jay talks to families about their personal experiences and their different conclusions.
Presented by John Humphrys. Producer CARRIE THOMAS Editor ANNE TYERMAN