I actually know several people who have a different than average number of fingers, from birth. My friends have been very open about what it's like coping with more or less fingers when the world simply isn't designed to accommodate them. One of my friends has fewer fingers than expected, but was determined to get a music major at a competitive music school and had to get accommodations for the piano requirements.
So I was excited to read this story. This book was written more like a fable, where little Billy is poor and his parents can't afford surgery to remove his "extra" fingers. Luckily, his extra fingers operate perfectly well, which isn't always the case, and Billy has incredible musical abilities even without instruction.
Although it's unrealistic, it's a cute story about how it's okay to be different. Thanks to NetGalley for letting me read this