He was born in Kabul in the mid-1960s and moved to Paris in 1976, when his father took a diplomatic posting.
The family was due to return to Afghanistan four years later, but the Soviet invasion meant it was not to be.
"I was very nervous," he says, "but I'm so happy with what Marc has done. There's something that transcends cultural barriers in this film: I've been at screenings and seen 80-year-olds and kids respond well."Forster's film paints a wistful portrait of childhood friends growing up in 1970s Afghanistan before foreign occupation and Taliban intolerance returned the country to the Dark Ages.
The story's protagonist, Amir, a Pashtun, escapes with his father during the Soviet invasion and settles in America.
But instead of highlighting Hannah's down-to-earth personality and potent pipes, Don insists she mimic Nadine's more refined, sophisticated image.
In a fit of pique, a lovelorn Don randomly selects the unassuming, insecure, yet beguiling Hannah Brown (Garland) from a saloon chorus line to groom as Nadine's replacement, and vows within a year to make her the sensation of both the 1912 Broadway season and New York's famed Easter Parade.
Hosseini, an urbane 42-year-old former doctor who lives with his wife and two children in northern California, sits in a suite in the Four Seasons Hotel in Beverly Hills and sighs.
"To me this is a positive story and yet I am a little irked when people call it a film about sexual privation.
Forster cast unknown Afghan children after he visited Afghanistan in early 2005 and shot the bulk of the film the following year in the Chinese town of Kashgar on the old Silk Road.
"I didn't want to misrepresent the country and was so relieved when Khaled said Kashgar reminded him of his youth in Kabul," Forster tells me.