The fertility watchdog has decided to relax the rules over the creation of so-called 'designer babies'.
The decision by the Human Fertilisation and Embryology Authority (HFEA) will mean that embryos can be screened and selected to help sick siblings.
The authority already allows embryos to be tested so families can weed out genetic disorders.
However any change in screening rules is likely to prove controversial and be opposed by anti-abortion groups who question the ethics of embryo selection.
Has the Human Fertilisation and Embryology Authority (HFEA) made the right decision? What are your views on selecting donor siblings? Are you happy for the law to change?
This debate has now closed. Thank you for your comments.
The following comments reflect the balance of opinion we have received:
All parents hope that they may be able to bear children who will make a positive contribution to the lives of others. Is this not an example of this - yet with a more specific rather than a general application?
Stuart Earl, Tyne and Wear
The irony about the 'designer baby' debate is that preventing hereditary diseases and birth defects is an imposition on 'diversity,' yet creating designer babies to solve the problems we refuse to eliminate is permitted. Either way, as a race we will begin to gain the knowledge needed to alleviate suffering. Someday, perhaps the fundamentalists here in the United States can be convinced that giving people better lives is not contrary to God's design.
Brendan Harnett, York, PA, USA
No, I do not think this is right. Everybody wants to have compassion on sick children. Who would argue against that ? But this is much more. It's manufacturing one human being to fix another. That's serious. People are not a means to an end. They're valuable in their own right.
Mark, Bristol UK
Is it better to live in a world where technological advances provide not only ways of improving our lives but also of making hazards greater? The more we advance the more I am pulled towards the belief that we are no better off than a hundred years ago -two, even three hundred years ago. Enlightenment? Industrial Revolution? What are we working "towards" if not our own, ultimate, destruction -regardless of moral or religious complaint?
I am 59, a Grandma and I agree. Why do they have to be called designer babies? They should be called saviour babies.
F. Williamson, Teesside England
I really don't like the sound of this. It's like something out of Michael Marshall Smith's novel 'Spares' where rich people keep their clones in special institutions for spare parts. We're not there yet but things are heading that way.
The term "designer baby" really annoys me. The embryos are not "designed" any more than the flowers in my garden are designed. Selected maybe, but not designed. Nature practices selection all the time. Why shouldn't we, especially where it will help another?
John, Luton, UK
Why not just screen the parents and if they are in the risk area screen the embryos and prevent the child being born with a genetic condition in the first place. This will save the hassle of having a second baby born and ensures the first is strong and healthy. Why not just screen every baby to ensure our children are all born with perfect genetic features? Was this not what Hitler wanted, a super race created through selective screening? This is all going to far and should be stopped before we alter the very fabric that makes us what we are.
What happens if (when?) the science goes wrong and it turns out the 'designer baby' cannot help the sick sibling? Will that baby still be loved as much by the parents? How will they cope with the disappointment? I think we have to tread extremely carefully and think through all the scientific, moral and ethical issues before allowing this form of genetic manipulation.
Richard, Glos, UK
I have lost one child and have one with a genetic condition. Do any of these people know what it is like to outlive your own children not due to an illness or accident but due to the fact you and your spouse are not compatible, genetically.
Sham Sultan, Birmingham
I don't know if they have made the "right" decision in the long run; I don't think that anybody is in a position to judge that. If the law-change was given due care and consideration, then, I am happy for it to have changed. If it was rushed through, like so many decisions are, then how can I support such a cause?
John, Glasgow, UK
I have every sympathy with parents of sick children who need stem cell treatment or bone marrow transplants. I am not a "pro-lifer" and do not object to embryonic research, as long as it is strictly controlled. But to create a real human being for the sole purpose of harvesting its cells to help an older sibling raises disturbing ethical issues. How will such a child react to its origins when it is old enough to understand? Siblings can be cruel to each other, and not just when very young. Shouldn't there have been a wider debate among the public and relevant expert professions before this landmark decision was taken?
Lesley Kettle, London, England
I understand the desire for parents in such situations to do everything they can to try to improve the situation for their child. However, I think that the technology should only be used where the parents have indicated that they are determined to take on the risks of a "natural" conception to try to provide a donor match.
Jeremy, Christchurch, New Zealand
This is all getting a bit scary if you ask me. The technology that exists to "screen" and choose embryos for the purpose of helping a sick sibling is morally wrong.
Michael, Medical Student, Norwich
I think it's awful that the rules have been relaxed. It will encourage parents to bring children into this world not because they want another child but just as a tool to help a sick sibling.
Bernice, London, UK
I think it is a fantastic move. If it helps a child live then it can't be bad. The "designer" child will be just as loved by parents who know all too well what looking after a child is like.
Kate, West Midlands