Does your child have what it takes to be the next Tom Brady or Mia Hamm? You can find out, according to a number of companies marketing genetic tests that claim to identify genes involved in the development of strength, speed, and other elements of athletic success. But not so fast: In this week's Journal of the American Medical Association, two pediatricians warn about the dangers of such testing. Here, a guide to the issue:

How do these genetic tests work?
Scientists have identified several genes and gene combinations that contribute to athletic traits. A gene called ACTN3, for example, is known as the "speed gene." Atlas Sports Genetics and other companies offer mail-order test kits that let people check which variant of the gene they have, to determine whether they might be better suited to endurance running or sprinting, for example. Some parents say this helps them direct their children to the right sports, according to Lindsey Tanner of the Associated Press. The basic Atlas test costs $169.

How popular are they?
Atlas has sold several hundred test kits since it began offering them in 2008, according to the company's operations president, Nat Carruthers. CyGene Laboratories, which sold a similar test, has suspended operations.

Why are doctors concerned?
"Skeptical doctors and ethicists say the tests are putting profit before science," says Tanner. For one thing, researchers are still a long way from fully understanding what role these genes play, so it's premature to claim that "ACTN3 can accurately and reliably identify future athletic stars," say Dr. Alison Brooks and Dr. Beth Tarini in the Journal of the American Medical Association. And, they say, having children specialize in specific sports early on "could lead to burnout, injury, or both."

Are there other problems?
Yes. Some doctors "see a major ethical dilemma" in testing children who don't fully understand what's happening, and may not be able to give informed consent. This type of testing "is elective at best and should actively involve the children in the decision-making process," says Dr. Lainie Friedman Ross of the University of Chicago, as quoted by the Associated Press. "This is recreational genetics with a real serious potential for harm." That's right, says Jeremy Olson in the Minneapolis Star Tribune. What if the tests show the kids "don't have the desired genes?" That could put a lot of extra pressure on kids.

What do the companies say?
“Our goal is to help people become the athletes they were born to be,” says Carruthers, as quoted by the Associated Press. The testing is not meant to exclude kids from any sports, or to tell parents "what their kid should do and how good their kid will be.”

Is this type of testing here to stay?
The FDA is considering whether these tests need to be regulated, but Dr. Alison Brooks, one of the authors of the JAMA commentary critical of the testing, says it's unlikely to go away. "My guess is we're going to see more of this, not less," she says.

Sources: AP, Star-Tribune, Journal of the American Medical Association