PARIS — It's been almost 20 years since the work of Scottish scientists Ian Wilmut and Keith Campbell led to the birth of Dolly the sheep, the world's first cloned mammal. News of the breakthrough rippled like a shockwave, provoking both enthusiasm and outrage. The biggest concern? That we might do the same with humans.

The European Council hastened to amend its Convention for the Protection of Human Rights and Dignity of the Human Being with regard to the Application of Biology and Medicine, prohibiting "any intervention seeking to create a human being genetically identical to another human being alive or dead."

In the two decades that followed, many other mammals were conceived through cloning, to such an extent that the South Korean company Sooam, created in 2006, now offers wealthy dog owners the chance to clone their pets after their deaths — for $100,000.

But humans themselves seemed sheltered from it, until now. Not so much because of ethical reasons, but because of technical ones. Geneticists hit a brick wall every time they tried to make such a "nuclear transfer" into a human being.

Their goal was not for a human Dolly to be born, which was forbidden all over the world after Wilmut and Campbell's experiment, but to obtain embryos that they'd allow to develop in vitro for a few days so they could be turned into stem-cell reserves. This so-called "therapeutic" cloning, authorized in various countries (Britain, United States, Japan, South Korea, etc. but not France) seemed out of reach for laboratories.

What was once impossible ...

That's no longer the case. A few weeks ago, Chinese doctor Xu Xiaochun said some things that would send shivers down anybody's spine. He is CEO of Boyalife, a company that has invested $31 million in a Tianjin factory to produce 100,000 cloned cattle embryos per year to meet Chinese demand. "The technology is already there," Xu said. "If human cloning is allowed, I don't think any other company will be in a better position than Boyalife to make it happen."

He didn't stop there. "Unfortunately," he continued, "the only way to have a child currently is to have it be half its mom, half its dad. Maybe in the future you have three choices instead of one. You either have 50-50, or you have a choice of having the genetics 100% from the dad or 100% from the mom."

Wow.

Strangely, Xiaochun's words went relatively unnoticed, as did a 2013 report by an American geneticist named Shoukhrat Mitalipov, from the University of Oregon, who succeeded in obtaining a human embryo through cloning that he allowed to develop in vitro for six days (until the blastocyst stage) before taking stem cells from it. His experiment was successfully reproduced a year later by two other teams.

Dolly, cloned ... then taxidermied — Photo: Mike Pennington/National Museums of Scotland, Edinburgh

One of the "tricks" that made this result possible was immersing the ovum in a bath of caffeine, which is indeed believed to block the cell-division process in a phase that increases the chances of a successful cloning.

The unknown

Nobody knows for sure what would have become of these human embryos had they been implanted inside a surrogate mother — whether they would have developed with abnormalities, resulted in miscarriage or made it to term but with mental or physical disabilities. Or, like Dolly, would they have become perfectly "healthy" newborns, with the caveat of having the same genetic makeup as another human being?

Despite the chilling, if not entirely groundless statements (the technology does exist) of Chinese entrepreneurs, the geneticist community doesn't seem to show great interest in the recent experiments of Shoukhrat Mitalipov and his followers.

Alain Fischer, a professor at the College of France and founding member of the genetic disease institute Imagine, brushes the issue aside with a sweep of his hand. "This whole issue has been null and void since the discovery of iPS cells," he says.

Developed in 2006 by Japanese scientist Shinya Yamanaka (who was awarded the 2012 Nobel Prize), iPS cells have revolutionized cellular therapy, which had been confined to embryonic stem cells. Now that there's another way that is technically simpler and ethically preferable to obtain stem cells, why bother creating embryos through cloning? Especially since supernumerary embryos are in large supply.

Hervé Chneiweiss, of the French Institute of Health and Medical Research (INSERM), says 170,000 of them are currently kept frozen in France alone, "more than enough to cover the population's needs in terms of embryonic stem cells."

But Chneiweiss believes human cloning enthusiasts aren't so much targeting ill people as the larger and more lucrative market of women who want to bear children at an older age — for example, after they've had a good career start. As they get older, they become less and less fertile. If they haven't found a partner by the time they could still give birth, Mitalipov's technique would allow them to have a nucleus sampled that could later be transferred into the oocyte of a younger woman.

This is also the opinion of Arnold Munnich, co-director of Imagine with Alain Fischer, who stresses how much he disapproves of colleagues who are pursuing human cloning. "People are waiting for us cure their children, or at least to find out what they're suffering from," he says before taking a dig at Mitalipov. "They don't concern themselves with the flights of fancy of Oregon-based researchers."