Do androids dream of electric ‘Dolly’ the cloned sheep? What became of the Brave New World

When Dolly the cloned sheep was born 20 years ago today, many hailed mankind’s new-found mastery over DNA as a ­harbinger of medical miracles such as lab-grown organs.

Others trembled at the portent of a brave new world of identical humans farmed for spare parts or as cannon fodder. As it turns out, neither came to pass. Human cloning – complicated, risky and ethically contentious – has largely been replaced as the holy grail of regenerative medicine by other technologies, say experts.

“It has not lived [up] to the hype,” said Rosario Isasi of the University of Miami’s Institute for Bioethics and Health Policy. “It was like a eureka moment: that we will finally be able to understand more [about] the mechanisms of disease, be able to maybe use it as a treatment for infertility. But that has not happened.”

Arguably the world’s most famous sheep, Dolly was the first mammal cloned using a technique called somatic-cell nuclear transfer (SCNT).

It involves removing the DNA-containing nucleus of a cell other than an egg or sperm – a skin cell, for example – and implanting it into an unfertilised egg from which the nucleus has been ­removed. In Dolly’s case, the gene-encoding cell was taken from a mammary gland, which saw the ewe named for buxom country singer Dolly Parton.

Once transferred, the egg reprogrammes the mature DNA back to an embryonic state with the aid of an electric jolt, and starts dividing to form a single-parent embryo. No human is known to ever have been created in this way. Cloning as a human reproductive technique remains taboo.

Apart from ethical and human rights objections raised to the creation of carbon-copy people, safety is a key concern. In animals, only a handful of cloned embryos survive to birth, and many have health problems later.