Can most Americans be ID’d by relatives’ DNA?

Illegal use of person’s DNA worries privacy advocates

WASHINGTON, Oct 13, (AFP): The remarkable technique used to identify the suspected “Golden State Killer” four decades after his crimes – genetic genealogy – could be used to identify half of all Americans from relatives’ DNA samples, a new study says.

And only a few years from now, the process could be used to track nearly all Americans of European descent by making DNA matches with distant relatives, the authors of the study predict.

The research, published Thursday in the US journal Science, could have wide-ranging privacy implications – if someone uses a consumer website to trace his ancestry, should that information be used to identify his kin, possibly in a criminal case?

“We are on our way to get to the point that virtually anyone will have a third cousin in those databases,” said Yaniv Erlich, the chief science officer at the MyHeritage website, and senior author of the study.

Predict

“I predict it will happen within two to three years.”

A person and his or her third cousin have the same great-great-grandparents. With a second cousin, one shares great-grandparents.

The closer you are with a relative, the more similar your genetic make-up is.

Even in the case of third cousins, the human genome – or the information encoded in a person’s DNA – is very much alike.

When police find a DNA sample that does not match anyone in their database, a criminal investigation can come to a dead end.

In California, police had been at that point for decades in the case of the socalled Golden State Killer, who is blamed for 12 murders and more than 50 rapes dating back to the mid-1970s.

Then they uploaded his DNA sample to a free website called GEDmatch, which allows users to post DNA test results in text format.

The site then generates a list of people with similar genomes, ranked from the closest to the most distant – with names and email addresses.

In the Golden State case, investigators hit the jackpot – the suspected killer’s third cousins popped up as a match.

Police rebuilt the family trees as far back as the 1800s... before wading through the hundreds of descendants to try to find their suspect.

By eliminating possible relatives by sex, age or residence, they landed on Joseph James DeAngelo, whose DNA they discreetly obtained from a car door handle and his trash.

That sample matched one left at the scene of a 1980 murder. DeAngelo is now behind bars awaiting trial.

Since that breakthrough, police departments across the country are using these techniques to try to resolve their cold cases.

Thirteen people have been arrested in five months, according to Parabon NanoLabs, a company that analyzed 200 mystery samples.

According to the company’s director of bioinformatics, Ellen McRae Greytak, 60 percent of those samples had “matches” on GEDMatch that were worth pursuing.

Parabon’s researchers work assiduously using publically available data (genealogy websites, Facebook accounts, LinkedIn profiles, obituaries, etc) to rebuild family trees and identify possible suspects.

Beyond the 13 cases that led to arrests, “we have several other ones where we’ve given them a lead of a single individual,” Greytak told AFP.