I wonder how big the Eastern Germanic influence (Gothic, Vandalic, Burgundian, etc...)is on modern Germanic Europe. And with that I mean mainly genealogical influence.

How much modern German(ic)s have an Eastern forefather ? Where are those persons mainly situated ? How large is the chance that native people of Bornholm, Usindom and Rügen are descendants of a Eastern Germanic tribe ? Are their any dialects possible influenced by an Eastern Germanic tongue ?