The real science of population genetics, he explained, is used to figure out how large groups of people moved and mixed over time. "I view these things as more for entertainment than anything else," Stoneking said. None of this means an ancestry kit from 23andMe or AncestryDNA or Nat Geo is worthless, Stoneking and Platt agreed. But that process is imperfect and clearly doesn't work the same way every time the companies run the rests, he said - though the errors aren't hugely significant.
(Live Science asked all three companies to explain the issue, but none gave a specific answer.) Įach of these companies, Stoneking said, breaks down the DNA in the spit sample into alleles - genetic markers that they use as raw data. But they agreed that it likely has something to do with their methods for converting a vial of spit into data for the computer to interpret. Neither Stoneking nor Platt was sure exactly why AncestryDNA had a 1 percent difference between its results for different samples, or Nat Geo had a 3 percent difference, or 23andMe had wiggle room that disappeared with the update.
#What i learned by checking my dna matches for a year plus#
"If they were to be completely honest, what they should tell you is not that you're 47 percent Italian but that you're 47 plus or minus some error range … based on their ability to distinguish this ancestry and other sources of error that go into the estimation," Stoneking told Live Science.Īnd it's clear that there are sources of error, he said. Mark Stoneking, a population geneticist and group leader at the Max Planck Institute for Evoluntionary Anthropology in Leipzig, Germany, agreed. (Image credit: Rafi Letzter/Live Science) It's not really weird to him that there's a 15 percent Jewishness gap between my results in Nat Geo and in 23andMe, he said. "There isn't really a right or wrong answer here, because there is no official designation of what it means to be Ashkenazi Jewish genetically." "It's not really science so much as it's description," he said. (In this case, Platt said, the company probably decided that since just about all Ashkenazi Jews have some genes in common with a mix of other European populations, it makes sense to call those genes Ashkenazi as well.) It was just another way of interpreting the data. So, when 23andMe changed its mind about my ancestry, the 100 percent answer wasn't more true. Non-Jewish European populations, he said, tended not to mix quite as much with others as people elsewhere in the world, so companies can easily draw finer distinctions between them.īut ultimately, it doesn't mean anything to be 35 percent Irish, or 76 percent Finnish. But those boundaries never really existed, and they aren't real things." And are trying to create boundaries within those clusters. "Certain peoples are more closely related to each other than to other peoples. "There is structure to history," he said. But that boundary, Platt said, is fundamentally "imaginary." And people who had one grandparent with that sort of DNA will hear that they're 25 percent Moroccan. To divide people into groups, Platt told Live Science, researchers make decisions: For example, they'll say, the members of this group of people have all lived in Morocco for at least several generations, so we'll add their DNA to the reference libraries for Moroccans. A person who calls herself an Italian today might have called herself a Gaul a couple thousand years ago and gone to war against the Romans. People move around, get together and separate. But that's not what human history looks like. Others came from that spot over there, and they were Middle Eastern. Some of your ancestors came from this spot, it says, and they were Central Asian. Log onto a website like Nat Geo's and it chunks the world up into different pieces. "So, you can't really say that somebody is 92.6 percent descended from this group of people when that's not really a thing." "Ancestry itself is a funny thing, in that humans have never been these distinct groups of people," said Alexander Platt, an expert in population genetics at Temple University in Philadelphia. Scientists who specialize in this sort of research told Live Science that none of this is all that surprising, though they noted that the fact that the companies couldn't even produce consistent results from samples taken from the same person was a bit weird. But probably (almost definitely) not.īut, of course, I already knew all that. And maybe somewhere in my family tree there was a Middle Easterner, or a Native American. The rest of my ancestors in recent memory probably also lived in Europe - though who really knows where. So, nine DNA tests later, I learned this about myself: I'm a whole lot Ashkenazi Jewish.
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