"It's very powerful information, and it can be a very difficult situation if you're telling somebody 'Well, we have your DNA results and it shows that you have such and such risk — maybe 100 percent risk in some of the testing that we're doing — of developing a particular disease, a serious disease, a crummy disease,'" he said. "It's very heavy-duty stuff, and it's difficult to be in that room and get that kind of information. It doesn't just go away as soon as they leave your office."
Critics say that because genetic testing is in its infancy the information 23andme provides is inevitably incomplete … they question its accuracy.
"It's like trying to deliver the news when you've only got a portion of the information and the facts available to you," Witt said.
Avey says the data are very accurate, but according to Witt, there are "many different areas in the human genome that are going to influence any one person's individual risk," which means "DNA can falsely tell you that your risk is low to get diabetes, or falsely that it's high based on three out of 20 of the markers."
If someone were to get a report that says they were at lower risk for diabetes, it's only part of the picture because Witt says there are 20 other genetic markers for diabetes out there that cannot be tested.
Good news might also lead to a false sense of security in that some people might decide to neglect their diet or cut back on exercise because they are a lower risk level for a particular disease.
No test can determine with complete accuracy whether or not someone will develop a disease, according to Avey.
"There isn't a single disease where there is one test you can take that would say yes or no. And its going to be a long time before we get there," she said.
Though I tempered my expectations, when I sat down to discover the secrets of my own DNA I was not entirely relaxed.
It turns out that my likelihood of having a heart attack is average.
"Genetics isn't all that plays into having a heart attack," Avey said. "Obviously there are a lot of environmental factors as well."
I don't have the genes identified as increasing risk for Multiple Sclerosis.
But when it came to my chances of developing Type II diabetes, the news wasn't as reassuring.
"It does look like you have an increased risk from 11.2 out of 100 to 19 out of 100," Avey explained.
"That's almost double the average risk," I said. "Wow. That is not good news."
The test also revealed what kind of muscle fiber I had.
Avey said I had "CT, which is what many world-class sprinters and some endurance athletes have."
This was especially interesting, because when I was a university student I played rugby and scored high on sprints.
Overall for me it was a reassuring experience and a reminder that I need to lose weight in order to avoid my genetic predisposition to obesity. While genetic science may enable researchers to develop better strategies for detecting and treating disease, it may be wise to tread carefully when it comes to your own DNA.
"We both fear and love the idea that somehow our genomes are us, that everything about us is defined by this long sequence of as CS GS and TS. You know, it's just not true," said Greely. "For most of us, the events that have happened during our lifetimes — our parents' efforts for us, the friends' we've made, the jobs we've had, the good and bad luck we've had — that's more important in who we are than what genes we're born with. And that's really important to remember."
"Genes are, except for a very few unfortunate people, not destiny, they're influences, they're not destiny," he said, "and if we think too heavily that they are destiny, we are going to mess ourselves up."