Although other experts say it is now biologically possible to clone a human, the ethics and legality surrounding such a possibility are a minefield.
Sinclair said, "Human cloning is banned in every country that I am aware of. I can think of no reason why you would want to clone a human and can see no benefit of it."
Another problem is that the efficiency of SCNT remains low, meaning that a relatively large number of cloned embryos generated in a laboratory are required to produce cloned offspring compared to natural conception or in vitro fertilization.
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"As with natural conception and IVF there are losses throughout gestation and in the period shortly after birth; it's just that these losses are greater with cloned embryos," Sinclair said.
Embryo loss, pregnancy complications and the deaths of newborns are still high as a result. Ethical concerns then remain concerning the welfare of cloned animals, despite the good health report for the Nottingham Dollies. Anecdotal evidence suggests that cloned cattle can also live long and healthy lives, once past the critical early life risks.
Bruce Whitelaw, a professor of animal biotechnology at the University of Edinburgh's Roslin Institute, told Discovery News that the new information about the health of the Nottingham Dollies is "another part of the evidence that animal biotechnologies can be successfully used."