LONDON - Religious groups are appalled by it, some scientists think it is inevitable and doctors believe the technology will hasten the search for new methods to treat incurable illnesses.
Like it or not, cloning is an issue set to dominate the political agenda, scientific research, newspaper headlines and dinner party conversations for the foreseeable future.
Whether it is reproductive cloning to enable the infertile to become parents or therapeutic cloning to create embryos so scientists can mine them for stem cells, the master cells of the body, few issues are as emotive.
The word conjures up images of armies of identical people, or desperate couples or partners wanting to replicate lost loved ones.
News that U.S. biotechnology company Advanced Cell Technology (ACT) had recently cloned a human embryo was met with outrage, skepticism and scientific consensus that it was premature to claim such an achievement.
The tragic events of September 11 put human cloning and the rapid pace of science back in the headlines and brought home the point that it is probably a question of when, not if.
``I think it is inevitable, unfortunately. I give it about five years,'' said Alan Coleman of PPL Therapeutics, the Scottish firm that helped to create Dolly, the cloned sheep, in 1996.
``There will be people who attempt it. I think it will prove to be rather unsuccessful generally and my big fear is that the people who attempt it will be the least competent to do it. The most competent just wouldn't do it,'' he told Reuters.
HUGE INTELLECTUAL CHALLENGE
ACT produced one six-cell embryo which is a long way from even a blastocyst, a cluster of 100-150 cells from which stem cells can be extracted.
Coleman believes ACT was ill-advised to release the information and said it confirms the difficulty of transferring animal work to humans.
ACT said it was not trying to clone a human but to produce stem cells to cure diseases such as Alzheimer's, Parkinson's, diabetes, cancer and AIDS.
Other researchers including Italian fertility specialist Severino Antinori, who helped a 62-year-old woman become a mother, and American scientist Dr. Richard Seed have both publicly expressed their desire to clone a human.
Seed believes it will be impossible to stop human cloning because it is such a huge intellectual challenge.
Coleman and many other scientists say that apart from any other moral or ethical issues, it is simply too dangerous because of the risk of miscarriage and creating deformed fetuses.
It took many unsuccessful attempts before sheep, cattle, mice, pigs and goats were cloned successfully.
``My particularly viewpoint is that in making it safe, the experimentation that is involved in refining the procedures is in itself immoral. I don't think one should get over the safety issue because it is immoral to try,'' Coleman said.
Despite his reservations and fears, Coleman said ultimately someone might be successful.
STILL A LONG WAY AWAY
Other scientists, including Dr. Ann McLaren of the Wellcome CRC Institute in Cambridge, England, believe human reproductive cloning is still a long way away because of the safety concerns.
``Nobody will seriously consider trying reproductive cloning in humans until the animal research has got much further along the safety and efficiency lines,'' McLaren told Reuters.
In the meantime, she thinks there will be more discussion as to whether there are certain scenarios in which human reproductive cloning could be ethical. The results may differ between countries, she added.
David King, of the independent monitoring group GeneWatch UK, believes a global ban on reproductive cloning will be in force before scientists overcome the technical challenges.
Therapeutic cloning -- creating embryos for a supply of stem cells that can be used for research or therapy -- may be just as far off.
``There is nothing therapeutic about the cloning itself -- it is just a step to making stem cells, which can then be used therapeutically,'' McLaren explained.
Many scientists believe stem cells, either from embryos or adults, offer tremendous potential to treat diseases and that research on both types of stem cells should proceed.
Robert Terry, a senior policy adviser at the world's largest medical charity the Wellcome Trust, said embryonic stem cells are easier to isolate and have the most potential to differentiate to other cell types.
Even if human reproductive cloning becomes a reality, Terry does not believe it will become common.
``The majority of people seem to have an instinctive reaction, which is the yuck factor, which I think will prevail,'' he said.