For as little as $100, here are some secrets you can unlock from your DNA: Whether you could have inherited a risk factor for certain kinds of cancer. Or how much of your genetic makeup comes from Neanderthals.
You might also learn whether your genes raise your chances of getting diabetes -- but your doctor will still probably be more interested in other, more obvious risk factors, such as your family history and diet.
In short, although technology is quickly making it cheaper and easier to get data about yourself, it's not always clear which information is worth getting and which isn't.
Here's a guide to using, and paying for, genetic tests.
What you can find out -- and what you'll pay
Roughly, two kinds of tests are available.
The first is ordered by a doctor and will often involve finding all the variations in specific genes. Research has found some variations that point to a higher risk of diseases, including breast cancer and a kind of colon cancer.
A doctor might recommend a screen based on risk factors like family history or ethnic background. Other tests, says David Fleming, an internist and health ethicist at the University of Missouri, can provide clues to how you'll respond to certain drugs or treatments.
The tests can cost $300 to $3,500. If your doctor recommends it, insurance will generally cover it like any other test. But call your insurer first: Some might require an advance letter from your doctor or a visit to a genetic counselor, a professional trained to help people use genetic information to manage their health.
The second kind of test is a home kit that lets you mail in a saliva sample and log on to a website to get results. It's generally not covered by insurance. (The Food and Drug Administration has said it's concerned about unregulated consumer tests but allowed companies to keep them on the market if they began the process of getting approval; none are yet FDA approved.)
One big player, 23andMe, has made a publicity splash by cutting its price to $99 for a report on up to 250 indicators, from that Neanderthal DNA to markers of health risk. This test may differ from one your doctor would order; it won't read all the variations in a gene but looks for common markers.
For concerns about a specific disease, use a doctor, not a kit.
Why you shouldn't face the serious stuff alone
Experts caution that the results of tests can be difficult to interpret on your own. That's fine if you are looking for fun info on your ancestry. But discuss with a counselor or doctor in advance whether you should do a screen for a disease, and what a positive or negative result would mean.
You also need to think about what you'll do if you get a worrying result.
A test can find markers of an elevated risk for late-onset Alzheimer's, for example, but you can have them and never get the disease. And since there's little to do now to prevent Alzheimer's, you may feel better off not knowing.
Other screens, such as those for cancer, could leave you with difficult choices about how aggressively to respond. "The issue is when we make decisions based on fear rather than what we know," says Fleming.
You'll want professional help to sort through the facts. Visits to genetic counselors are often covered by insurers and billed like doctor's visits. You can find a counselor at nsgc.org.
What tests don't tell you
With some diseases, such as diabetes, it may be more accurate to simply look at your own family history, says Michael Dougherty, director of education at the American Society of Human Genetics. What's more, he adds, "the genetic test doesn't take into consideration all of the environmental factors."
So it's a good idea to eat right and exercise no matter what the result.
How safe are your records?
A law passed in 2008 prevents health insurers from using genetic information against you. Employers can't use it either. But federal law doesn't offer the same protection on long-term-care, life, and disability coverage. (Some states have stricter rules.)
"The concern is the insurance company could require you to show certain medical records," says Harvard Medical School geneticist Robert Green. Or even just ask if you've been tested. It doesn't appear to be happening yet, but it's one more thing to keep in mind as you weigh whether you want to see what's written in your DNA.