DNA Testing Kits: How Accurate Are They?

(CBS) — People are turning to DNA testing kits to determine their ancestry. But can you trust the results?

CBS 2’s Mai Martinez put three of the most popular ones to the test, using her DNA. As you’ll see, she had some surprises.

Says Martinez: I’ve always known my mother was Vietnamese and my father was Cuban, but due to the Vietnam war, the Cuban Revolution and other tragic circumstances, little is known about my ancestors. So, I thought sending my DNA to three testing companies might provide some answers. Dr. Lee Shulman, Northwestern’s chief of clinical genetics, guided me through the results.

Not surprisingly on her mother’s side, her information came back 46.1 percent Chinese and Vietnamese.

But on her father’s side, some Irish heritage, 6 percent, was detected.

“This is not necessarily that you have Irish relatives. You have a genomic sequence that may be similar to what is found in the British Isles,” Shulman says.

“I said the only thing that would surprise me is if there’s something like Irish or Scottish,” Martinez says.

That wasn’t the only surprise AncestryDNA found.

While their results showed Martinez’s DNA was primary East Asian, 41 percent, it also found links to Southern Europe, primarily Italy and Greece, and to the Iberian Peninsula, primarily Spain and Portugal, as well as a 5 percent link to Great Britain, 1 percent link to France or Germany and 1 percent to Africa.

Shulman says the mix is not surprising, given that Cuba has drawn from a variety of nationalities.

“I also have an affinity for the Vikings, so I’d like to see something from Norway and that area,” Martinez’s father tells her.

Martinez also registered 3.1 percent from the Baltics, according to MyHeritage, which also found Mai Martinez’s DNA to be 36.7 percent Iberian, 2.5 percent Italian, 2.9 percent North African and 2.8 percent Middle Eastern.

The service 23andMe found similar results, but upped the Italian to 3.3 percent and added a 1.4 percent French and German.

So, why the differences between tests?

Dr. Shulman says each company uses its own algorithm.

“While the specific numbers may be slightly different, I think they have all accurately assessed your ancestry,” he tells Martinez.

The tests ranged in price from $69 to $99. Ancestry was the fastest at returning results, taking about two weeks. 23andMe took about 2 ½ weeks, and MyHeritage took a little more than a month.

Dr. Shulman says these tests can be entertaining, but people cannot count on them for any medical diagnosis.

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