Designer babies were once the stuff of science fiction and Nazi experiments.
But the advance of technology means this futuristic concept has entered the realm of real science.
Scientists say it will soon be possible to genetically modify humans to protect against and prevent disease and improve traits like intelligence, beauty and strength.
Genes could be altered to change people’s skin, hair and eye colour.
At the heart of the controversy is a gene-editing technique known as CRISPR.
This technique allows scientists to delete and insert pieces of DNA into certain cells.
It could lead to cures for diseases, more efficient food production and, ominously, things like bioweapons.
But concerns have been raised about the safety of such techniques and the prospect of them being used to create designer babies.
As such, the thought of playing god to reshape humanity is an increasingly fraught and ethically-challenging subject.
Professor Rodney Scott, head of medical genetics at University of Newcastle, is among the wary.
“Personally, I don’t like the concept of designer babies,” said Professor Scott, who is also director of molecular medicine for NSW Health Pathology North.
“If you look at it from an evolutionary perspective, you’re going to weaken the gene pool and create a weaker species in the longer term.
“Once you start choosing particular features, you start narrowing genetic choice.”
It’s also a field with the noble aim of correcting genetic errors that cause disease, but caution is needed.
“One needs to step back and think – in a particular population where a disease is particularly prevalent – is there any reason why it has become so?”, he said.
“Is there an advantage to that individual or group of individuals to carry this particular disorder?”
Professor Scott supports using gene editing to improve crops.
“People need to look at this with their eyes open.”
He said genetically-engineered crops had built resistance to disease and reduced the use of poisonous herbicides and pesticides.
The federal government has sparked a fresh debate on this subject, with a “technical review” of gene technology regulations.
Australia’s Office of the Gene Technology Regulator said the review was “focusing on technologies that can be applied to a wide variety of organisms”.
This included “crop plants, animals, microbes and humans”.
“However, regulation of the application of these technologies to humans is outside the scope of this review,” a spokesperson said.
“Altering the genome of an embryo and then attempting to achieve pregnancy is prohibited under the Prohibition of Human Cloning for Reproduction Act 2002.
“Research involving human embryos is regulated under the Research Involving Human Embryos Act 2002.”
Nevertheless, the possibility remains that CRISPR technology could be used on humans in Australia in future.
Scientists in China have reportedly used this technology on cancer and HIV patients.
The first human trials of CRISPR-based treatments could begin in the US and Europe as early as this year.