In 1990, 4-year-old
Ashi De Silva became the first person to be treated for a fatal disease with gene therapy. Such treatment is still rare, but the fact that many of the genes responsible for inherited diseases, such as cystic fibrosis, have been located, means that test-tube eggs which carry them can be discarded, and only healthy eggs returned to the body.
Thus the Ashe family know that their second child will not have to suffer as their first has.
But such breakthroughs have repercussions. Not only health, but also looks and intelligence could be influenced by genetic engineering. Once we start re-designing our children where will we stop?
"The line dividing those who should be changed and those who could be changed will be very hard to fix, " says David Suzuki in the fifth part of this series which look at the human stories behind the latest DNA discoveries.
Producer Andrew Liebman
Executive producer Robin Brightwell