Who is Uncle Nematollah from Funny in Farsi: A Memoir of Growing Up Iranian in America and what is their importance?

Uncle Nematollah is Kazem's little brother. He is a physician in Iran. While visiting Kazem for several months, he sampled every American fast food he could find. After eating Amrican style, Uncle Nematollah had to work off two inches from his waist before he returning home.