Who is Baba from The Kite Runner and what is their importance?

Baba is Amir's father. He is a wealthy and well-respected man who harbors a secret. Baba had relations Ali's wife and Hassan is his illegitimate son. Amir feels that he is a disappointment to Baba. He feels physically weak and meek in Baba's presence. This is turned around when Baba withers away with cancer in San Francisco.