This friend was saying that she was in Church one day when she was very young following along in the hymnal. She noticed how the little dots moved up and down when the people sang up and down. It dawned on her that she could do that with her voice, too. She did not know how to read yet, but she figured out that following the music notes just made sense.
Every Sunday, Bob and I would sit together during Church practicing reading the hymn music. After a while, Bob told me that the other notes were other parts and we could practice singing those parts, too. Which we did. It got to be a sport. On each verse we sang a different voice part. Over the years, we got pretty good at singing all of the voice parts and holding our own parts against each other, too.
Our mother had us part-singing from the time we were very young. She said it was a sign of intelligence if you could hold your own part. In fact, there were times when we would get into heated arguments over who had to sing the melody. None of us wanted the stigma that we couldn't hold our own on a harmony part
Oh, the joys of being raised in a musical family...