عزيزي الحر (f) شكرا على جهودك.
ربما كان سؤالي مبهما. وجدت المقالة التالية من الديلي تلغراف الانكليزية و هي تشير الى أن هذه الفحوص -حاليا- لا تعطي النتائج بدقة جيدة , و لا تزال العلاقة بين الجينات و توزع الأعراق غير واضحة . وهناك مثال فيها على أختبارات على أشخاص من الشرق الأوسط و من حوض البحر الابيض المتوسط و من الهند, وجدت أن لهم من فترة قريبة أجدادا من سكان أمريكا الأصليين !
One test they studied "finds evidence of recent Native American ancestry in many people from the Middle East, India, and the Mediterranean region of Europe,"

هذا هو المقال.
http://www.telegraph.co.uk/earth/main.jhtm...sciances119.xml

The limits of gene ancestry tests

Last Updated: 6:01pm BST 19/10/2007

Some companies are making unreasonable claims about their power, reports Roger Highfield

A warning has been sounded about the limits of DNA tests that claim to reveal racial ancestry, by a panel of scientists and experts.

Researchers are concerned that consumers do not understand the limitations of commercial genetic ancestry tests that can fuel misconceptions about race and genetics.
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In Britain several tens of thousands of people have had their DNA tested, at a cost ranging from £50 to £500 while in America half a million people have been tested in the past six years.

Although these tests can identify related people who share a common maternal or paternal ancestor and also locations where people with genetic similarities are found today, they actually provide no information about most of the test-taker's ancestors, only look at a tiny fraction of their DNA, and can suffer false negatives and positives.

Most important, the DNA tests are silent on the issue of race, which has no scientific meaning.

Deborah Bolnick of the University of Texas, Austin, and colleagues explain in the journal Science that, though some researchers see these tests as merely "recreational genetics" or "vanity testing," the problems can be significant for the test-takers, who may hope to identify biological relatives, validate genealogical records and fill in gaps in their family histories. "Test-takers may reshape their personal identities, and they may suffer emotional distress if test results are unexpected or undesired."

Some are searching for a "homeland," which is particularly poignant for many African Americans, who hope to recapture a history stolen by slavery. But "since contemporary notions of race, ethnicity and identity reflect a tangled web of social and biological factors, it is problematic to assume that they can be determined by a genetic test."

"Consumers often purchase these tests to learn about their race or ethnicity, but there is no clear-cut connection between an individual's DNA and his or her racial or ethnic affiliation," says the paper.

One test they studied "finds evidence of recent Native American ancestry in many people from the Middle East, India, and the Mediterranean region of Europe," says Dr Bolnick. "Such a result is very surprising since there is no other evidence that Native Americans migrated to those regions in the recent past or had contact with the populations in those regions."

"Not all companies make clear the limitations and assumptions underlying these tests," Dr Bolnick added. "Because it is important for consumers to understand what the tests can and cannot tell them, we are encouraging professional genetic and anthropological associations to develop policy guidelines regarding genetic ancestry testing."

Prof Bryan Sykes of Oxford University, who leads the DNA testing company, Oxford Ancestors, uses two basic kinds of test (Y chromosomes and mitochondrial DNA) to trace male and female ancestry respectively, so people can trace relatives and geographical origins. "We have never had a serious complaint about people being upset about the results, in tens of thousands of tests," he said yesterday.

But he stressed that his company does not offer "racial profiling" because, as the Science paper points out, "these tests are based on scientifically invalid assumptions and we believe they can lead to potentially dangerous misunderstandings about racial purity."

He agreed with the conclusions of the paper and warned that the "myth" of pure races and ethnic groups "was exploited to the full by the Nazis."

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