Your DNA's in the post

Fancy being told you have a higher-than-average chance of getting prostate cancer but are at low risk of glaucoma? Now for about £500 you can have your genetic make-up analysed. Rob Liddle swabbed his cheek and sent off for a scan.
An e-mail pops into my basket to say the results of my genetic scan are ready. I have a few minutes free - shall I take a peep now or wait until I can devote the time to digest the results properly?
Curiosity gets the better of me and I log on to the Decodeme website to view my password-protected "gene profile".
This is quite exciting - could what I find out in the next few minutes alter the course of my life? I'm curious by nature, but that doesn't extend to wanting to know when the Grim Reaper is going to come a-knocking.
Up pops a list of grisly conditions - most of which are familiar to me, indeed some of them lurk in my family history.
And it's the ones that have touched my life that I am drawn to first. I click on Heart Attack, bypass the warm-up "introduction" to the condition, and head straight for my own "risk summary".
I'm told: "According to the selected literature, the relative genetic risk calculated from your genotype for males of European ancestry is 0.90.
"This corresponds to a 44.2% lifetime risk of developing heart attack, which is 10% less than for males of European ancestry in general."
Fated to be fat?
So far so good, I suppose, but that's still a high risk and I'm not celebrating with a full English breakfast yet.
I scan the list of 25 traits again and settle on Crohn's disease. Here I'm told the research indicates that I have a lifetime risk 1.42 times the average. Not so good. But for Diabetes, types 1 and 2, better news.
Next I plump for Obesity - surely a banker. These genes make me look fat, right? No, a lower-than-average risk. I can't use that as an excuse for my fuller figure.
A number of personal genomics firms, including Iceland-based Decodeme and 23andme and Navigenics, in the US, are now directly selling tests to the public that assess genetic risks of suffering from certain conditions.
Some also provide information about your ancestral origins.
After receiving a sample taken from the inside of your cheek, Decodeme analyses up to one million DNA markers, annotates them and puts them in the context of disease risk, providing you with a personal profile.
'Do more exercise'
One reason the tests have proved controversial is that they can measure only the genes that studies have linked to certain conditions - not the many that have yet to be discovered.
Decodeme says it is continually adding the results of new research to its database, improving the accuracy of the existing risk summaries and extending the list of traits for which you can assess yourself.
But there are other risk factors that could easily override these genetic indications, such as family history and lifestyle. My genetic risk of getting type 2 diabetes is rated as below average, but being overweight probably counts for more.
Steve Jones, author and professor of genetics at University College, London, believes that, in most cases, individual genes cannot say much about a person's risk. For him, potential customers would be better off following the advice of the health lobby.
"It is a new form of diagnosis - before any symptoms manifest themselves - but really what everybody should do is smoke less, eat less and do more exercise," he says.
The Decodeme website has a section on risk factors and prevention for each of the conditions featured, which I later peruse.
From this I learn that the prevalence for Crohn's is highest during the second and third decades of life - but that it can crop up in the over-70s. I'm 42, so may have dodged that bullet.
And if I still have questions, I can message Decodeme's team, who may then refer me to a genetic counsellor.
But for some critics, discovering your risk of developing a serious condition from a web page rather than a doctor presents a serious problem - even if the scans are unlikely to throw up any catastrophic results.
The authorities in some states in the US have recently warned testing companies that they should not continue to solicit business from residents unless the process is being sanctioned by a licensed physician.
'Reduced autonomy'
Daniel Sokol, a lecturer in medical ethics at the University of London, says the absence of the direct doctor-patient relationship does create a problem.
"The results could allow people to make changes for the better to their lifestyle," says Dr Sokol.
"However, if they misinterpret them - the scans could do more harm than good and could actually reduce people's autonomy if they interpret the results incorrectly or exaggerate their implications."
But Kari Stefansson, chief executive of Decodeme, says it should be a matter of personal choice how people treat their own data.
"The people who feel that they want to go over the results with a doctor should go to a doctor," he says.
"When I got mine, I went into the office and closed the door. I wanted to be alone.
"It should be your decision - we are not ramming it down anyone's throat. How you use it depends on who you are, but you are entitled to make the choice of getting the information or not getting it.
"But you can get so much out of it - it could be extremely beneficial to know that you are at a higher risk."
Dr Stefansson admits that the cost of the test at $985 probably puts it out of reach for most people, but he predicts a future in which accessing such personal genetic information will be commonplace - with the tests possibly costing a 10th of what they do now in five years' time.
We go through my results together. I appear to have a slightly increased chance of suffering macular degeneration (an eye problem), coeliac disease and Crohn's, but there is nothing in my risk summary that indicates that I need to take further medical advice immediately.
"I'm afraid to tell you that you are just an average guy," jokes Dr Stefansson.
Perhaps this news is the hardest of all to take.