I have tested my DNA and learned a lot about how where my ancestors might have been 500 yrs ago.
Results give you estimates in regards to your ethnicity and the region it encompasses. I learned something more than what my past few generations said they were. DNA does not lie, if nothing else it confirms what you know, but I believe it can also show how your European heritage is influenced by history and culture over time.
For example the Swedes spent a lot of time nearly 400 yrs ago in Pomerania, in what was part of Germany until 1945. So my DNA indicates that I have Scandinavian ethnicity. This was one interesting finding about my history that was never known in the last 100yrs or so.