Can you re obtain German citizenship after giving it up?

Question

My father fled East Germany after WW 1 and became a Canadian citizen. He now wants to try and re obtain his German citizenship and have both Canadian and German. I'm not sure if this is possible. He has lived here for most of his life, but has made trips back to Germany and still has relatives there.

Answer 1

Ask the German authorities.

Answer 2

No. Germany would require him to give up his Canadian citizenship. Germany does not allow dual citizenship after the age of 23.