How do DNA tests that promise to reveal who your ancestors work | Science and health

In recent years, complete sequencing of the human genome has facilitated public access to DNA tests to discover our genetic history. Or at least that's what they promise.

These kits can be purchased at many pharmacies and also on the websites of specialized companies and even at Amazon. And they are becoming cheaper: if, about five years ago, a kit cost about $ 300 and can be bought at $ 75.

These tests were even the best-selling products in November in the United States during the last Black Friday, according to Amazon data.

Functioning of DNA Tests

The test that promises to reveal the identity of our ancestors works as follows: you buy the kit, you spit it into a tube or you pbad a cotton swab to it Inside the cheek and you send the sample. for the company with which he contracted the service.

The company extracts salivary cells that contain the entire genome. Your DNA is then inserted into a database and compared to the genome of other clients who have paid for the same service. These similarities and differences are thus established and an ethnic map created. But what is the reliability of these tests?

Distorted information

Scientists warn that, in fact, the genetic profiles obtained through these tests can not provide very accurate information about our ancestors.

In the BBC's Curious Case Studies of Rutherford and Fry, as well as an interview with geneticist Mark Thomas, these genetic tests were examined.

"Many of these companies have provided you with a report of their ethnicity, so they do not really tell you who their ancestors are, but whether their genetic characteristics match some of their ancestors' descendants," said Thomas.

Normally, this type of test does not compare its DNA to that of people who lived in the past, but to that of his contemporaries.

But the comparison is limited to those who appear in the company's database. Therefore, in many cases, reading your genome can produce different results depending on the company you recruit, warns Thomas.

Favorite Ancestors

People have the preferences of their ancestors. Thomas explains that it's more appealing and more exotic to say that his ancestors were Viking or Celtic royalty for example than the Gauls.

But the truth is that in Europe, almost all Europeans who do not have a recent migratory past are very likely descendants of the Vikings, says the expert.

"Going back in time, up to the time when the Vikings lived, a European will surely discover that one of his ancestors was Scandinavian, because these people occupied a vast territory and s & rsquo; Were developed to the north of Africa. "