In 1996, Dolly the sheep made headlines around the world after becoming the first mammal to be successfully cloned from an adult cell.
Some people suggested that human clones could play a role in eradicating genetic diseases, while others considered that the cloning process could.
Some people suggested that human clones could play a role in eradicating genetic diseases, while others considered that the cloning process could.
Eventually, eliminate birth defects (despite research by a group of French scientists in 1999 finding that cloning may actually increase the risk of birth defects).
There have been various claims — all unfounded, it is important to add — of successful human cloning progams since the success of Dolly.
In 2002, Brigitte Boisselier, a French chemist and devout supporter of Raëlism — a UFO religion based on the idea that aliens created humanity — claimed that she and a team of scientists had successfully delivered the first cloned human, whom she named Eve.
However, Boisselier was unwilling — or indeed unable — to provide any evidence, and so it is widely believed to be a hoax.
So why, almost 30 years on from Dolly, haven't humans been cloned yet? Is it primarily for ethical reasons, are there technological barriers, or is it simply not worth doing?
"Cloning" is a broad term, given it can be used to describe a range of processes and approaches,
but the aim is always to produce "genetically identical copies of a biological entity," according to the National Human Genome Research Institute (NHGRI)
Any attempted human cloning would most likely utilize "reproductive cloning" techniques — an approach in which a "mature somatic cell," most probably a skin cell, would be used, according to NHGRI.
The DNA extracted from this cell would be placed into the egg cell of a donor that has "had its own DNA-containing nucleus removed."
The egg would then begin to develop in a test tube before being "implanted into the womb of an adult female," according to NHGRI.