The Martian Child: A Novel About A Single Father Adopting A Son
David Gerrold
 A single man who writes science fiction books and screenplays for a living, adopts a son who claims he is from Mars. The adoptive father comes to be intrigued by the possibility his son might really be a Martian. Ultimately, the father realizes that he loves his son whether or not he is a Martian. The son uses a magical "Martian wish" to be a human so he can remain with his father.