What do you think a DNA test will tell you?

For one to several hundred dollars, you can have a DNA test done. Before you order that test, ask one simple question: what will you do with the results? Even more pertinent may be: what will the company do with the results?

The New York Times on Sunday presented the story of Georgia Kinney Bopp--a genealogist with a mission. Should you happen to run into her, keep your mouth closed--literally. Ms. Bopp travels with a DNA kit and can be very persuasive. Ms. Bopp apparently cornered a second cousin in Reno, Nevada, pulled out a DNA kit, and convinced him to give her a sample.

To me, the interesting part of the story was the description of how limited the information is that Ms. Bopp gets when she gets results from a DNA test. According to the article,

DNA tests can deliver surprises. In some families, someone may discover, for example, that he or she lacks a DNA connection to their supposed blood relatives.

What would you do if you learned from a test that your mother was not your mother, or your grandfather was not your father's father? It happens. Is it accurate?

One DNA test will not be enough for much family history testing--even for a paternity test you need samples from both the supposed father and the child. So, if you're searching for your ancestors, prepare to pay for more than one test.

The article goes on to state:

The  DNA tests have limitatiions, showing only small slices of genetic history. Here is why: a popular test, the Y-DNA, analyzes the chromosome that is passed virtually unchanged for generations from father to son. . . .Another test looks at mitochondrial DNA, a form that is passed from a mother to all her children. Both men and women can take the test.

The Y chromosome test tells you about only one male ancester in a generation, and the mitochondrial test tells you about only one female ancestor. . . .It doesn't take into account the fact that if you go back just 10 generations (300 years), you have 1,024 ancestors in that generation. Just seeing one ancestor, means you're looking at a very small slice.

Now, what does the company do with your DNA and/or the results of your test? If the results are fully anonymous, how do they send you the results? Will they add your DNA results to their database so others can check their DNA against yours? Did you hear about  the adolescent who found his "anonymous" sperm donor through DNA database information on the Internet? 

Have you ever wondered: How many kinds of DNA tests are there? Will you be able to understand the test results when you get them? What does 99% exclusion, 75% inclusion mean? If you "relate" to a tribe now living in Africa, does that mean your ancestors came from Africa? If you're black, but your DNA is 79% European and 21% Asian, are you still black?

None of these questions address the more dangerous side of DNA testing--the medical side. If you have a test for a "breast cancer gene" and the test result says you have a 50% chance of developing breast cancer, do you schedule a double mastectomy? Will your insurance pay for it? What will you tell your sister or your daughter about their chances of developing breast cancer?

Please don't  blindly order a DNA test and send your personal genetic code off to some company you've only read about through an advertisement. Check into things first. It's too late once the results arrive.

Marie Godfrey, PhD