WHEN PROTO PUBLISHED “YOUR GENOME, YOURSELF” (SUMMER 2008), the trend of mail-order genetic tests—offered directly to consumers by such companies as 23andMe, Navigenics and deCODEme—was just emerging. Since then the hype has only grown; to celebrate dropping the price of its service from $999 to $399, 23andMe hosted a “spit party” (guests provided saliva samples for DNA testing) for New York glitterati during the city’s Fashion Week last September. What is also growing, on the part of some scientists and state regulators, is concern that such tests could prompt consumers to make poor health care choices—either by requesting unnecessary additional tests to investigate one of the risks their genetic tests have uncovered or by finding justification for not changing bad habits. Now several studies are examining how people respond to genomic testing and whether it inspires them to make positive lifestyle changes such as giving up cigarettes.

The Coriell Institute for Medical Research in Camden, N.J., plans to enroll 100,000 people in a long-term study (it has recruited 3,300 so far) on using DNA testing to manage and improve health care. Participants will be surveyed periodically about ways the tests have influenced their behavior: Have they found the information useful, opted for further testing or experienced anxiety?

Scripps Translational Science Institute, Navigenics, Microsoft and gene-chip maker Affymetrix are collaborating on another study that will periodically survey people who have received a genetic scan to examine the scans’ effects on their behavior, diet and psyche. In both this study and Coriell’s, participants will receive an analysis of their genetic risk for a variety of conditions that might be changed by lifestyle.

Meanwhile, researchers at the National Genome Research Institute are focusing on the more fundamental questions of whether healthy people even want to know their genetic risk for disease and whether they’ll seek additional information after receiving the results. For this study, 300 or so people were screened for genetic variants associated with eight common health conditions. They are being tracked to see whether they later seek more information by, for example, collecting a personal family health history. Before researchers can reveal the impact of genetic tests on behavior, says Colleen McBride, co–principal investigator of the study, “we have to find out whether people understand the tests. Can they appreciate that the tests are only part of the story? And do they seek out the fuller story?”

With little federal oversight of genetic testing, some state officials are continuing to take action. During the past year, the New York State Department of Health and the California Department of Public Health each sent letters informing online gene-testing companies that they are violating state laws. Both states require that tests be ordered by physicians and that the companies have valid permits. Most companies are working to achieve compliance (sometimes by proving that they employ physicians who review customer orders).

Yet skeptics contend that even using a physician as a filter is of little benefit. “It’s becoming easy to figure out risk,” says James Evans, a professor of genetics and medicine at the University of North Carolina at Chapel Hill. “What’s difficult is figuring out how to use those risks to improve health.”