D.N.A., SCHMEE-N.A.

Oprah Winfrey caused a stir recently when she told an audience in South Africa that, in an effort to learn more about her ancestry, she had had her DNA tested--and found out that she is a Zulu. It's a tribute to Ms. Winfrey's fame that her comment in Johannesburg was reported as far away as Australia and India, although some accounts suggested that West Africa--the epicenter of the slave trade--is a much more likely site of genetic origin for an African-American.

The truth is that, wherever Ms. Winfrey's forebears came from, there is no DNA test that can magically pinpoint anybody's distant or "deep" ancestry, Zulu or otherwise. Even so, many Americans--including some who would rather die than have the FBI know what books they bought--are busy sending their genetic blueprint to companies and organizations that offer ancestry tests.

Not everyone can be a Zulu, dear.

Practitioners advertising skill in the fine art of interpreting DNA results are finding clients. And no wonder, judging by this Q&A on an ancestry-testing Web site: "If I see my mutation in the chart pointing to a sub-clade why should I test? Answer: You see your HVR-1 mutations only! That can simply be the result of homoplasy (Remember it is a 'hot spot' region!). You must confirm the sub-branch (when possible) with the coding region mutation that stands for a unique event polymorphism."

As impressive as that may sound, a geneticist we asked said it was gobbledygook and basically meaningless. So is much of the ancestry testing game. As true scientists in the field of genetics know, human beings are very similar genetically, and the variations that do exist can be found in virtually all populations. The best that could honestly be said to test-takers is, for instance, that they might have an ancestral connection to a certain region of the world. Given the limits of current hard science, DNA testing can offer less reliable information than old-fashioned genealogy and family trees.

Science. Again!