British geneticists took surname information from an area formerly settled by Vikings to see if men living there today who had Scandinavian surnames also had evidence of Scandinavian (aka Viking) genetic ancestry. They analyzed the Y-chromosomes of several hundred men, and, not surprisingly, found that those with Scandinavian surnames did indeed have Scandinavian DNA, at least on the Y-chromosome. Similar studies of Irish men have also found a modest connection between surnames and Y-chromosome types.Surname DNA ProjectsAs we reported several weeks ago, the field of genealogy has been invigorated by the increasing use of genetic testing to fill in the missing branches of a person’s family tree. Genealogists are now comparing their Y-chromosomes to those of others with the same surname, to see if a shared surname is also an indication of the shared ancestry. Within the past few years, surname DNA projects have sprung up all across the world – with hundreds of genetic genealogists digging deep into their genes as they piece together their detailed family trees.Surnames and ForensicsBy far one of the most interesting applications for surname and Y-chromosome comparison is in the field of forensic science. In 2006, British geneticists found that — for some of the more rare surnames such as Maloy or Rivis, there was a strong connection between surname and Y-chromosome haplogroup. The authors reasoned that, if DNA were to be recovered from a crime scene, forensic investigators might be able to narrow down the possible perpetrators to a specific subset of surnames.However, there are several limitations to this idea — namely the fact that most men in the UK have rather common surnames, such as Smith, Green, and Adams. Men with these surnames have a wide range of Y-chromosome DNA types, so it would nearly impossible for investigators to use the Y-chromosome to locate a suspect. However, on principle this idea has merit, and further advances along these lines may someday allow investigators to exploit the DNA-surname connection.One final note: 23andMe customers need not worry that their data will be used in this way – our research database does not include surnames and our terms of service do not allow us to share data with law enforcement unless we are legally compelled to. And even if such a situation did arise, we have publicly committed to resisting legal requests for customer data.