"he learned it from a family member years previous"

Yes, he learned it as a young boy. Worth remembering that at least some of the singers who furnished our ballad collections will have learned their songs as children (this seems to have been a common mode of familial transmission - not unlike reading the kids a fairy story before bed), and then been asked by collectors to recall them many years later. F J Child's most revered ballad singer Anna Brown came into that category.

Which raises questions about recollection and recreation that don't arise with a singer who performs his party piece in 'The Ship' every Saturday night.