So B. It by Sarah Weeks

Heidi has an unusual family consisting of herself, her severely mentally retarded mother, and her agoraphobic neighbor. Heidi has never questioned her life circumstances and has been fairly sheltered since the neighbor also homeschooled her. New and old mysteries begin to pop up that trouble Heidi.  What is her mother’s real name; it can’t be So B. It, can it? Where’s the rest of her family (father, grandmother, etc) and where does she come from? But most puzzling, what does her mother mean when she says “soof”? Heidi ventures out on her own, travels out of state following clues, and demands answers. The answers aren’t as satisfying as Heidi had hoped, so reader BEWARE this has some tearjerker moments.

Read an interview of the author for more information.