I think Celtic music has a powerful effect on people especially when combined with a Celtic heritage. The sounds of a culture that have been handed down through what I call your "genetic memory" have got to be powerful and deeply intimate on some unconscious level as well as superficially. When the listener is consciously aware of this cultural connection, the music has even more impact. I'm sure this is true of all cultures and all music.

On the other hand, the music itself, when it's good, will affect anyone. I'm not Celtic but am still very moved by O'Carolan, and unmoved by some of the less imaginative and repetitious jigs and reels.