Actually Goldberg is just a stage name..her real name is Karen Johnson.. As for her ancestry..most African American people have atleast some..(and sometimes alot) of European ancestry..
Anyway..claiming European ancestry is just something Americans (along with the other colonized countries)do..The truth is that it's not every accurate..but for some reason it's needed.
But her whole basis for saying she has Scottish anscestors is her "real" second name and the fact that she likes the country. In an interveiw she said that she visited the country and felt "a real spiritual connection" so she thinks she has links to here. I visited a strip bar a few months ago for a stag party and felt a real "spiritual connection" there. Does that mean my great grandmother was a stripper? Or even my great grandfather? No.
When she does an interveiw for German, Italian or French T.V she probably says the same thing.