There is no way will would have learned to play the piano by himself, do you think his mom or friend taught him how to play the piano, this is from the pilot episode ???

https://www.youtube.com/watch?v=n3eJkf4erbI
https://www.youtube.com/watch?v=n3eJkf4erbI
https://www.youtube.com/watch?v=n3eJkf4erbI