According to Genesis 9.20–27, Ham saw his father Noah lying drunk and naked in his tent, and Noah later cursed Ham's son Canaan, pronouncing him a slave to his brothers. Ham's precise offense has been interpreted as castration, sexual assault, and incest. But the simplest explanation seems best: in failing to cover his naked father, Ham was disrespectful. Still, it is not Ham but his son Canaan whom Noah cursed, almost certainly because the story served to legitimate Israel's conquest of Canaan and the destruction of its inhabitants.
This passage has more recently been used to support another kind of racism. Because some of Ham's descendants, notably Cush, are black (see Gen. 10.6–14), the “curse on Ham” has been interpreted as black (Negroid) skin color and features in order to legitimate slavery and oppression of people of African origin. This interpretation occurs first in the Talmud and has persisted in certain circles. It is also reflected in the postbiblical Christian tradition of three Magi, one of whom is black, in parallel to Noah's three sons. Yet it was neither Ham nor Cush who was cursed, but Canaan, the “brother” of Cush and the “son” of Ham.
Steven L. McKenzie