When Kaleb said that his brother was the black sheep of the family, he is using a metaphor. The phrase "black sheep" is a metaphorical expression that refers to a family member who is considered different, rebellious, or deviant compared to the rest of the family. It implies that the brother stands out or doesn't conform to the expected norms or values of the family. The metaphor draws a comparison between the brother and a literal black sheep, which is a deviation from the typical white sheep in a flock.