This rings true to my experiences with High School Choir. Tone matching was a skill that everyone was able to improve in, with just two notable exceptions.

There was one girl who was truly tone-deaf, and as a result could not tell that she was only ever singing one monotone note.

And then there was the teacher's son, who would run sound during our productions and claimed to have perfect pitch. He certainly could pick up on things much quicker than anyone else running the boards.