I really expected better from someone who studies ethnicity and related DNA. Let's look at some of the examples: Hungarian look like other people from central Europe. Finns look like other people from North Europe. But Ugro-finn people from their native land (Siberia) are actually Mongoloid. Turcic people in Asia are also Mongoloid, but Turks in Turkey look pretty much European. Conclusion: when Hungarians/Turks arrived to Europe, it was actually relatively small number of people* that somehow conquered locals and eventually made them speaking their language.
Another example: distribution of B blood type in Europe isn't related anyhow to ethnic borders (with a notable exception of Basks). Conclusion: ethnicity has no foundation in biology.
Another example: in ancient Balkans, there have lived many nations, well described by Greeks and Romans: Illyrians, Tracians, Dacians, Celts. They have all disappeared long time ago, but there is no mention in history that there was any sort of war, genocide, famine or anything similar that could have annihilated not one but several nations**. Conclusion: entire nations may disappear in process described in the first example.
*) compared to the local population
**) some of them remained, but not in all areas where they originally lived; Celts and Tracians disappeared completely