A swipe of blood, semen, saliva or any other DNA-carrying bodily evidence at a crime scene can help implicate a suspect—if the police have one handy. But if there’s no one under suspicion, the DNA is largely useless.
However, now researchers at the University of Leicester and the University of Essex in the UK have developed a method for linking genetic material to a last name. This discovery means that forensic scientists may eventually be able to use DNA to help determine the identity of a suspect, or at least narrow a search down to a few pages in a phone book.
The Y chromosome, which determines maleness, is paternally inherited, like most surnames in England. So, the researchers collected two groups of 150 men with one man in each group sharing a last name with a man in the other. The surnames ranged all over the spectrum of regularity, from very common ones like Smith to the much less common such as Attenborough or Grewcock. Then the scientists tested for Y chromosome similarity among their pairs of men with the same last name.
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“We didn’t think there would necessarily be a link,” said Turi King of the University of Leicester, the principle author of the study, which was published in the February 21st issue of Current Biology.
King pointed to complicating factors, like illegitimacy, adoption and multiple originators, which would increase the chances that two people with the same name would not be biologically related. Names like Smith derive from occupations, and so could be expected to have had many originators, while names like Attenborough are based on locality and would only be assumed by people who descend from a common place.
“You might have the same surname, so on paper it looks great, but in biology, it’s not the same thing,” King said.
Overall, King and her team discovered that they could predict a man’s surname by matching his DNA with that of another man with the same last name about 20% of the time. For names that were in the bottom 80% of the regularity spectrum, they could up their success rate to about a third of the time.
While this percentage of accuracy could never be enough to convict, King hopes that her work will act as an initial step for investigators in cases without any suspects. She is currently applying for funding to build a wider database of DNA-surname pairs, across all of Britain’s ethnic groups.
“It might be a starting point,” she said. “If [the police] go to a crime scene, they’ve got the DNA. They can analyze the Y-chromosome, put it in this database and see what surnames it brings up.
“It might let them prioritize the suspect list.”