Designer babies already here
BACK in 1962, when Marvel comics introduced Spider-man, the scariest technology imaginable was nuclear energy. So the comic-book hero Peter Parker got his super powers from the bite of a radioactive spider.
In its latest incarnation, as a Hollywood movie franchise, the Spider-man myth has evolved — now it is a genetically-modified (GM) spider's bite that turns him into a vigilante web-spinner.
The shift reflects public fears about technology. In Britain, experimental fields of GM crops designed to reduce the use of pesticides and boost production are torn out of the ground by protesters who claim they are "decontaminating" the land.
France has banned GM corn, though the European Food Safety Authority has rejected the move.
And in Canada, the University of Guelph has, due to lack of funding, abandoned its "enviropig" research, which added mouse DNA to the pig genome so that porkers could digest phosphorus, cutting the need for dietary supplements and the amount of pollution in the animals' waste.
Yet these are nothing compared to the storm that is about to break over the issue of GM humans.
The report in the Daily Mail last week that a team of scientists in New Jersey led by Dutch embryologist Jacques Cohen had created mutant humans with three genetic parents, two mothers and a father each, was not exactly news.
The children were born in 1997 (conicidentally, the same year that Ethan Hawke starred in Gattaca, a film about a future dominated by genetically engineered people) and the scientific article that appears to have inspired the newspaper was from 2000.
At the time of their birth, the technology was seen as just another new infertility treatment.
But the fuss on the Internet this time has been intense. The idea that scientists are on the verge of creating a super-race of humans fills many people, including lots of other scientists, with foreboding.
Among those stepping up to condemn the research by Cohen's team last week was Lord Winston, the emeritus professor of fertility studies at Imperial College London and presenter of more than a dozen TV documentaries, including the prize-winning 2003 show Threads of Life.
Talking to the BBC last week, he said there was no evidence that the technique was worth doing. "It would certainly not be allowed in Britain."
The method used by the Cohen team is not quite ready to produce super-heroes, let alone super-villains. It does not involve the the DNA in the nucleus of each cell which codes for features such as maximum height, number of toes, and eye colour.
Instead it involves mitochondrial DNA (mtDNA), found in tiny organelles inside each cell that help to convert sugar into energy. Some scientists believe that mitochondria were once independent life forms that were swallowed by our ancient, single-cell ancestors and harnessed rather than digested.
Mitochondria are inherited only down the maternal line, hence their use a few years ago to identify Eve, the mother of all humanity, as a woman in East Africa 200,000 years ago.
When an egg cell's mitochondria are not working properly, the embryo may fail. Cohen's approach to this infertility problem is to inject cytoplasm — the gel-like substance that fills a cell — from a donor to the recipient. It was intended as a last resort for women who had undergone repeated unsuccessful IVF treatments.
Of the 30 children born so far from treated eggs, two have been shown to have the extra mtDNA. Washington Monthly reported in 2002 that one of those children had been diagnosed with "pervasive development disorder", a type of autism.
There was no evidence that the mtDNA was to blame at the time, but the role of mitochondria in diseases ranging from diabetes to Lou Gehrig's was still unclear.
The ethical dilemma of designer babies is likely to become more fierce as GM technology advances.
Who could argue, for example, that terrible genetic diseases such as cystic fibrosis, Down syndrome, haemophilia or sickle-cell should not be removed from the gene pool.
The problem comes when parents decide they want to enhance their children with an extra few inches in height, a few more IQ points or a prettier face.
And if parents can do those things to their barely conceived offspring what's to stop them adding extra digits or limbs or perhaps a spare heart.
It's the stuff of science fiction today. But technology has a habit of racing ahead before society decides on the ethics.