Just in case you were wondering: yes, Donald Duck appears to be of Scottish descent. Though there is also some weird inter-species shit going on to the far right of that tree. Ewww.
This guy has diagrammed family trees for many Disney characters. (And you thought you had no life.) It's interesting that the Duck family tree seems to be the most extensive-- is this because he did the most research on it, or because Disney produced the greatest amount of source material based on Donald Duck?
Try not to let that keep you awake tonight.