10. Although, idiomatically speaking, sheep are known as followers, there are, as always, exceptions to the rule. But what colour makes these wayward dissenters stand out -- idiomatically, that is?
From Quiz The Year of the Sheep
Answer:
Black
The phrase, "a black sheep in the family", came about due to the occasional birth of a (literally) black sheep to a white flock. The phrase is also one which has negative connotations, both literally and metaphorically. Idiomatically speaking, a "black sheep" is known as a wayward member of the family, and one who doesn't follow suit. In addition to this, in nineteenth-century England a black sheep was considered to be a sign of the devil. Moreover its wool was far less sellable than white wool, as it could not be dyed.