The selection of music by ear: a genius or skill? Thinking

It is no secret that many children study at a music school without linking their future profession with music. As they say, just for yourself, for common development. But what is interesting. Communicating with graduates of music schools, one can often encounter a paradoxical phenomenon: children freely read notes from a sheet, expressively play complex classical works, and at the same time find it difficult to pick up accompaniment even to Murka.