After her critically acclaimed and commercially successful film Zindagi Na Milegi Dobara, filmmaker Zoya Akhtar is working on her next script wherein she will probably cast real-life cousins Kareena Kapoor and Ranbir Kapoor as reel-life brother and sister. This bit of information is already known. However, what is still a well-kept secret is the fact that this film could actually be an autobiographical one, and is based on the lives of the Akhtar siblings Zoya and Farhan. While one insider confirms, “Zoya’s next is a film based on Farhan and her growing up years.’’ Another one adds, “The film is not really a blow-by-blow account of Farhan and Zoya’s growing up years. It is a very sensitive script and is based on siblings. Only it draws liberally on some of the emotional conflicts and the bonding instances in Zoya and Farhan’s real life.” Talking about the script, Kareena Kapoor had told us earlier, “I’m very keen that Zoya finishes her script soon. I’m constantly in touch with her. It’s a terrific script, and I’m dying to work with Ranbir.’’ Of course even Kareena probably doesn’t know, or conveniently forgot to tell us that the brother-sister script is reportedly based on an autobiographical account of the Akhtar brother-sister duo. Zoya and Farhan are a year apart and Kareena is two years older than Ranbir. One also hears that though Kareena and Ranbir are the first names that come to mind for a project such as this, insiders say that the casting is still wide open. Zoya remained unavailable for comment.