Study: DNA websites cast broad net for identifying people
NEW YORK About 60 per cent of the U.S. population with European heritage may be identifiable from their DNA by searching consumer websites, even if they’ve never made their own genetic information available, a study estimates.
And that number will grow as more and more people upload their DNA profiles to websites that use genetic analysis to find relatives, said the authors of the study released Thursday by the journal Science.
The use of such databases for criminal investigations made headlines in April, when authorities announced they’d used a genetic genealogy website to connect some crime-scene DNA to a man they then accused of being the so-called Golden State Killer, a serial rapist and murderer.
In general, such searches begin on a site by finding a relative linked to a DNA sample. Then sleuths can use other information like published family trees, public records and lists of survivors in obituaries, plus whatever they know about the person whose DNA began the process. They can build their own speculative family trees. Eventually, that can point to someone whose DNA is then found to match the original sample.
With DNA databases “you need just a minute fraction of the population to really identify many more people,” said Yaniv Erlich of Columbia University, an author of the study.
Each person in a DNA database acts “as a beacon that illuminates hundreds of distant relatives,” said Erlich, who is also chief scientific officer of the MyHeritage website.
His paper focused on Americans of European descent because such people are over-represented in DNA databases, which makes it easier to find relatives.
The researchers started with the 1.28 million participants on the MyHeritage site at the time they did the work. Most had a northern European genetic background. For each, they looked for relatives more distant than first cousins elsewhere in the database.
About 60 per cent of the time, they found someone whose genetic similarity was at least equal to that of a third cousin, similar to the degree of relatedness that led to the Golden State Killer suspect. Third cousins share great-great-grandparents.
With some basic assumptions about what kind of data would be available for a criminal suspect, the researchers calculated they could pare down the possible identity of the initial person to just 16 or 17 people. That’s limited enough that police could zero in with further investigation, Erlich said.
Erlich and his co-authors suggested that such searches could cast a broader net in the near future. A database with DNA profiles of just 2 per cent of a population is enough to match nearly everybody with somebody who’s as closely related as a third cousin, researchers said. From that, they calculated that the genetic profiles of about 3 million Americans of European descent could deliver the equivalent of a third cousin for more than 90 per cent of that ethnic grouping.
Websites are getting very close to that, said Erlich, noting that MyHeritage now has more than 1.75 million participants. He said the website does not allow forensic searches.