Ancestry.com has improved the ability of AncestryDNA to find good matches for Jewish, Hispanic and other ancestries that maybe weren’t so precise before. Here’s the lowdown, quoted liberally from Ancestry.com’s press release:
The problem: Predicting genetic relatives among customers of Jewish and Hispanic descent and some other groups. “In DNA matching, we are looking for pieces of DNA that appear identical between individuals,” says the release. “For genealogy research we’re interested in DNA that’s identical because we’re both descended from a recent common ancestor. We call this identical by descent (IBD). This is what helps us to make new discoveries in finding new relatives, new ancestors, and collaborating on our research.”
“However, we also find pieces of DNA that are identical for another reason. At one extreme we find pieces of DNA that are identical because it is essential for human survival. At the other, we find pieces of DNA that are identical because two people are of the same ethnicity. We call these segments identical by state (IBS) because the piece of DNA is identical for a reason other than a recent common ancestor. This, we have found, often happens in individuals of Jewish descent.”
“The challenge in DNA matching is to tease apart which segments are IBD, and which ones are IBS….Most Jewish customers find that we predict them to be related to nearly every other Jewish customer in the database….Detecting which cousin matches were real and which ones were bogus has always been a challenge for these populations.”
First step toward a solution: “By studying patterns of matches across our more than half a million AncestryDNA customers, we found that in certain places of the genome, thousands of people were being estimated to share DNA with one another–likely a hallmark of a common ethnicity. Our scientific advancements… have allowed us to effectively “pan for gold” in our matches–by throwing out matches that appear to only be IBS, and keeping those that are IBD.”
“While the problem was more pronounced in customers of Jewish and some Hispanic descents, we observed this problem across all ethnic groups. So, all customers will see increased accuracy of their DNA matches, and significantly fewer ‘false’ matches.”
AncestryDNA results with better matches found by this method “will be available in the coming months,” says the release. They plan to email existing customers when results are ready.