Danes are remarkably genetically homogenous, researchers from Aarhus University report in Genetics this week.
The researchers enlisted Danish high school students to take part in a genomics literacy project and many of the participants also provided the 800 DNA samples and demographic information that then fueled this examination of the Danish population. The samples were analyzed used 23andMe's service.
Aarhus's Thomas Mailund and his colleagues then focused on the subset of their sample whose grandparents were all born in Denmark and compared their genetic profiles to data from other European countries. From this, they found that the Danish samples clustered with Norwegian and Swedish samples and were close to British, Dutch, German, and Polish samples in a principal components analysis.
When they then zeroed in on samples from students with three out of four grandparents from the same region of Denmark, Mailund and his colleagues were unable to uncover geographic clustering.
"I personally was surprised to see that all classical methods for detecting genetic 'structure' in populations failed to pick up strong signals. Even cutting-edge methods returned very similar "mixture profiles" for all regions in Denmark," first author Georgios Athanasiadis from Aarhus says in a statement.
The researchers note that their study did not touch on recent migrations to Denmark that have increased the country's ethnic diversity.