Fortune-telling on genes
"Genetic tests for origin are based on assumptions"
Short translation of the material Gizmodo about how inaccurate human gene research is.
Kristen Brown's family history is very unusual. Her grandfather–swarthy, with thick black hair–thought for a long time that his parents were poor Mexicans. But when he found the adoption papers, he went to the orphanage where he grew up and found out the name of his biological mother.
After meeting her, Grandpa Brown found out: he is a Syrian. After this incident, none of his children and grandchildren doubted their roots. However, everything changed when Kristen Brown's aunt underwent a genetic test from AncestryDNA.
Kristen Brown's Grandparents
The results were extremely unexpected. So, the aunt hardly had the genes of ancestors from the Middle East – only 16%, and not the expected 50%, because her father, in his opinion, was a pure-blooded Syrian. The rest of the analysis provided more questions than answers.
Usually, Brown writes, the countries of the Caucasus include, for example, Armenia. But the Ancestry test included Syria in this region, which gave another 15%. The remaining 30% (out of the estimated 50%) came from Greece and Italy. The data completely stunned Brown's aunt and mother, who, having done the test, received similar results.
This led to a small family quarrel. Grandpa Brown's mother was born in Pennsylvania, but lived in a closed Syrian community. She got pregnant in her teens by her father's best friend. The fact that he was also a Syrian has never been questioned.
Aunt Kristen Brown spent more than one day searching for Greek-Italian roots, even met with her father's biological mother, but found nothing. As a result, the journalist wondered: who is she really?
Gradually, the family discord gained momentum. But what if the mistake is hidden not in family histories, but in DNA tests? To find out, Kristen sent samples of her saliva to three companies: AncestryDNA, 23andMe and National Geographic (the magazine cooperates with Helix, which sequences the genome), and then compared the results of their analyses. They turned out to be very different from each other.
Results provided by AncestryDNA
Test AncestryDNA revealed that Brown has Middle Eastern, Caucasian and Southern European roots to the same extent as her mother (which is surprising). The test was not mistaken, determining the presence of Scandinavian ancestors – Kristen's father is from Norway.
The results of the analysis from National Geographic also showed the presence of "oriental" genes in Brown's DNA.
But unlike AncestryDNA, the National Geographic test determines only the region to which DNA samples can be attributed, which also affects the results – Brown belongs to a certain "Jewish diaspora" by 9%.
At the same time, there was less "Scandinavian" in the journalist than in the AncestryDNA test. Unexpectedly for her, the analysis showed a large proportion of Eastern European roots.
Results provided by National Geographic
The most striking (in a bad way) were the results from the company 23andMe. According to the report, Brown was only 3% Scandinavian, which, based on family history, is absolutely wrong. A very small share (5.5%) fell on the Middle East region. Kristen was also surprised by the dominance of Northwestern Europe - it accounted for 62.5%. And the test simply did not find Eastern European roots.
Results provided by 23andMe
To clarify the analysis from 23andMe, the author uploaded the data to the GenCove website, which helps determine whether genes belong to a particular region. But the journalist did not receive a clear answer.
The same data processed by different companies gave contradictory results – GenCove showed that 8% of Brown's DNA comes from the Indian subcontinent, 23andMe did not find anything like that.
GenCove Genetic Map
Four tests, the results are hardly similar. It turned out that there are a number of factors affecting the accuracy of the analysis.
First, genetics is a comparative science. To get data about genes, it is necessary to compare them with others. This method is initially imperfect.
Secondly, according to British geneticist Adam Rutherford, we completely do not understand the tasks of such genetic tests.
They don't show your DNA's past, they show its present.
Therefore, it is not surprising that the journalist's aunt turned out to be 30% Italian – just a comparison of her genes with others showed a lot in common with the genome of the inhabitants of modern Italy. But no matter how big the database is, and Ancestry, for example, contains information about six million people, an approximate estimate remains it. It turns out that only the amount of genetic information collected determines the accuracy of the analysis.
Thirdly, such databases are entirely created by clients, and this also distorts the data. After all, the fewer samples of, say, Middle Eastern genes a company has at its disposal, the more likely it is that there will be no "Oriental" trace in your results, no matter how pronounced it may be.
Finally, different tests look at different sections of DNA, different alleles from different parts of the genome. Also, each company uses its own algorithm for processing the received data. Rutherford, a native Briton, for example, found a small number of genes of indigenous peoples of the United States.
But for him, this is just a statistical error – the indicator was so small. In addition, a certain set of markers for accurate analysis has not yet been developed, so companies invent it in the process. Even GenCove director Joseph Pickrell was confused when he saw the spread of Brown's genetic data.
The genes of all people coincide by 99.99%, says Kristen. But we pay more attention to what separates us. We pay for unsubstantiated results. It should be remembered that genetics presupposes, not determines.
Companies engaged in consumer genomics do not hesitate to make loud statements like "DNA determines your identity." But this is not the case. Culture is not your genes.More precisely, culture is not limited to just one gene, everything is much more complicated.
In the end, the journalist's grandfather, having learned about his origin, did not change at all. He was and remained a Mexican. You don't have to be Italian to love pasta. Therefore, you can search for yourself as much as you want, Brown concludes, and genes have absolutely nothing to do with it.
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