I "learned" other people's harmonies (written harmonies on hymns, Ian & Sylvia's harmonies etc) very naturally, and sang them happily. But I didn't really start adding spontaneous harmonies until I joined the Folklore Society of Greater Washington and found that a lot of melodies on chorus songs were out of my range. :-) Now I thoroughly enjoy the challenge of finding a "good" harmony.

But what I like best is to lead a song that has a strong chorus or refrain, and to get back really fine harmonies and strong singing on the chorus. There is nothing like having a song be transformed, I guess I would describe it as taken to its full potential, by a group of people singing it together.