Genesis 9:24–25 (ESV)

24 When Noah awoke from his wine and knew what his youngest son had done to him,

Noah woke up from his stupor, and was told what happened. Noah then pronounced the curse on Canaan. This is a prophecy, just as in Genesis 9:27–29. An important question here is why Canaan is cursed and not Ham. Surely Canaan did not put Noah to shame, but his father Ham did...! Our response to this is based on the totality of the Bible as the one Word of God. It is impossible for the Lord to make a son pay for his father’s sin, provided that that son is in no way guilty of it (see Ezekiel 18:1–32). It is notable, for example, that the family and associates of Korah, Dathan, and Abiram were killed; yet Korah’s sons were an exception (see Numbers 26:9–11). It is clear that Korah’s sons did not participate with their father in the rebellion against Moses and Aaron, and thus against the Lord.

The most probable thing in these verses is that Canaan is the son who openly stood strongly behind his father. He actively participated with his father and showed the same spiritual attitude. The Lord then struck Ham in the son who supported him in his sinful attitude and speaking. God’s judgment, then, is clearly a punishment on Canaan’s own sinful life and attitude.

The punishment that came upon Canaan and his descendants is that they would occupy a very low and despicable position in the world—especially when you compare it to what was going to happen to the descendants of Shem and Japheth. We see God’s judgment upon Canaan and his descendants in a special way when the people of Israel entered the land of Canaan after the exodus from Egypt. God's people then killed and drove out the Canaanites. Even then this did not happen without the fault of the Canaanites themselves. Their sins have then become so great that they rightly deserved this punishment (see, e.g., Genesis 15:16). In this text, the Canaanites are called Amorites. A large proportion of them were then killed by the Israelites (descendants of Shem) or made into their servants.