Strangemaps summarizes the conclusions being drawn from this map and related data:
Genetically speaking, Finns and Italians are the most atypical Europeans. There is a large degree of overlap between other European ethnicities, but not up to the point where they would be indistinguishable from each other. Which means that forensic scientists now can use DNA to predict the region of origin of otherwise unknown persons (provided they are of European heritage).
The Dish 