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Millions of Americans post our ancestry information online. New research is showing just how easy it is for law enforcement to use this data to zero in on relatives who may have committed a crime. NPR health correspondent Rob Stein has the details.
ROB STEIN, BYLINE: Police made headlines last spring when they finally nabbed a suspect for a series of brutal rapes and murders in California from the 1970s and '80s.
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UNIDENTIFIED PERSON #1: Has the Golden State Killer finally been captured?
UNIDENTIFIED PERSON #2: California investigators used gedmatch.com to name Joseph James DeAngelo as a suspect in a...
UNIDENTIFIED PERSON #3: Used genealogy websites to try to identify the notorious Golden State Killer.
STEIN: And that was just the beginning. Police around the country have started doing this same sort of thing to solve other cold cases. So Yaniv Erlich at the company MyHeritage wondered, just how easy is it to use databases like his to find people?
YANIV ERLICH: We wanted to quantify how powerful is this technique to identify individuals.
STEIN: So Erlich and his colleagues analyzed the DNA from more than 1.2 million people in this company's database and discovered something startling. For more than 60 percent of people of European descent, they could identify a relative as distant as a third cousin. Most of the people in this database are white.
ERLICH: Each person in this database is a beacon that illuminates hundreds of distant relatives. So it's enough to have your third cousin or your second cousin once removed in these databases to actually identify you the same way that a GPS system uses multiple satellites to find a location.
STEIN: And when the researchers combined their data with other information like where a person probably lives and how old they are, they could quickly zoom in on a suspect.
ERLICH: Of course you need the genealogical records. You need to do the work. But you have enough power to get very close.
STEIN: And Erlich used the same technique to identify a supposedly anonymous woman whose DNA was stored on a National Institutes of Health Research database, raising questions about how anonymous these supposedly anonymous databases really are.
ERLICH: This technique doesn't only - can get you criminals or you can catch criminals with this technique. But you can also use this technique for other purposes, maybe purposes that could be illegitimate.
STEIN: So Erlich says the findings raise questions about how genetic information could be misused.
ERLICH: The police currently is using these techniques to find these really like, you know, murderers and bad people. But are we OK with using this technique to identify people that - I don't know - in a political demonstration that left their DNA behind? Are we OK with it if foreign governments are going to exploit this technique to identify U.S. citizens for their own purposes? So there are many scenarios that you can think about misuse.
STEIN: Now, many people defend the use of these techniques to help solve serious crimes.
ELLEN GREYTAK: I was excited to see this demonstration that genetic genealogy is so powerful.
STEIN: Ellen Greytak works at Parabon Nanolabs, which helps police solve crimes this way.
GREYTAK: We're working on these cases that, you know, haven't been able to be solved for decades. They are all either homicide or sexual assault. And some of these are just - I mean, they're horrific, you know, murders of children, things like that. It's just things that need to be solved.
STEIN: And Greytak says it's not nearly as easy as this new research may make it sound. But others argue that the findings underscore the need to make sure people know what they're getting into when they agree to give up their genetic information. Erin Murphy is a New York University law professor.
ERIN MURPHY: If it comes out tomorrow that they can use genetic information for something that feels a little unsavory, it's going to be virtually impossible to claw back the information that you've put out into the world. And more importantly, you've made a decision not just for yourself but for your siblings, for your distant cousins, for people you don't even know you're related to, for your children, for your children's children.
STEIN: So Murphy and others think better ways are needed to protect people's DNA to make sure it isn't misused. Rob Stein, NPR News.
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