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Why now though? The science behind gene testing is not new. What has changed, and rapidly, is the cost of technology.
Since the three-billion-US$ Human Genome Project was completed in 2001, sequencing an individual's genome "has become an order of magnitude cheaper and faster" every couple of years, Lynda Chin, a researcher at the Dana-Farber Cancer Institute in Boston, said in an interview.
The price tag today is about 100,000 dollars, and at least one company, Pacific Biosciences in Menlo Park, California, says it will be able, by 2013, to map all three billion base-pairs of a person's DNA in a quarter of an hour for a few hundred dollars.
But not everyone is ecstatic. To start with, the tests available to date are only snap shots of a DNA snippet, not the whole shebang. More critically, the data they yield is subject to interpretation.
"All of these tests carry a high degree of uncertainty," said Arnold Munnich, a researcher at the Centre for Genetic Medicine at Necker Hospital in Paris.
French genetics expert Segolene Ayme says "many of the kits currently on offer are simply scams". Most diseases or conditions are caused by a complex web of genetic and environmental factors that are hard to tease apart, these scientists explain.
Only a handful – so-called Mendelian diseases, such as muscular dystrophy and cystic fibrosis – are caused by mutations in a single gene.
By contrast, nearly 20 genes have been linked in studies to Type 2 diabetes, and at least as many can play a role in different forms of cancer. More are likely to be added.
So even if the tests in question are accurate, the real problem is how to interpret the data they yield.
There is another danger: if it falls into the wrong hands, the same data that might lead to early diagnosis or targeted treatment of a disease could become a reason to refuse employment, insurance or a bank loan.
Last year U.S. President George W. Bush signed the Genetic Information Nondiscrimination Act to outlaw such abuses, but enforcement remains a concern. Other countries have yet to follow suit.
Finally, the most vexing question may be this: do we really want to know everything that our genome has to say? That we have a 20 per cent greater chance of falling into dementia by the time we are 70, or that we are prone to alcohol or drug abuse?
