A member of a family or other group who is considered undesirable or disreputable. Black is usually considered for something negative in such idioms, like black magic etc.

People say "black sheep of the family" to make reference to a person that is not living according to the family rules or mores. Bad or good? who knows !!!! It's all in the eye of the beholder ... And it's not white because is boring , I mean, everybody is already white, let's put some difference ! =p by the way : bbbaaaa baaaaaa... I've been called like that my whole life ! =D

a black sheep means somebody very different ))) it is an idiom!

I think the simple answer is that sheep are usually white. So being a black sheep means you clearly are not like the rest of the (sheep) family. "Black sheep" doesn't always have a negative connotation. For example, if a family of accountants and academics has a daughter who is a very talented painter, she would still be called the "black sheep", only because she is so different.

The black sheep of the family= (idiom) the worst member of the family. The term originated from the occasional black sheep which are born into a herd of white sheep due to a genetic process of recessive traits. Black wool was considered commercially undesirable because it could not be dyed. From Wikipedia, the free encyclopedia