Did they explain it? Maybe there is a reason?
Net, I don't know if you got an answer to your question about why Anthony's parents had the shrine thing going.
Anthony nearly died when he was very small. That's when he had the tracheotomy. They were told he probably wouldn't even be able to speak again, much less sing.
That's why I'm so fascinated every time he opens his mouth to sing.
I suppose that's why they are so overjoyed with every achievement of Anthony's.