Ruthsatz and colleagues investigated the cognitive profiles of 18 prodigies: eight music prodigies, five math prodigies, and five art prodigies. Math and music prodigies had a significantly higher total IQ score than the art prodigies. In fact, the art prodigies had about an average IQ score.
While it's true that many prodigies receive support, resources, and encouragement from parents and coaches early on, their support is typically the result of a demonstrated "rage to learn." The reason why they are so driven to deliberately practice in their domain requires explaining.