Sleuthing via consumer DNA service extends reach

NEW YORK — About 60 percent 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 yesterday 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.