A surprising number of traditional musicians in the US born late 19th early 20th century tell the same story about how they learned to play.

Here's what you do.

If one of the parents doesn't already play guitar, they need to start learning. This might be the tricky part.

Anyway, you want a parent who is a musican who plays regularly within the home.

Buy a guitar and hang it on the wall. But make sure the instrument can be reached easily by the child. Then tell the child that s/he is forbidden to touch the instrument. But make sure that the child has ample opportunity to be alone in the room with the instrument.

Apparently worked every time.