This article mentions some DNA information that has been uncovered.

http://themountaineer.com/article/man-amnesia-seeks-information

"He can sit in a restaurant and tell you why it is working well or what needs to be improved," she said. Fitzpatrick works for an organization called Identifinders International, located in Huntington Beach, California. Testing has shown that Benjamin's DNA is shared by people located in eastern Tennessee, north Georgia and the western parts of North Carolina and perhaps to families with the surname of Davidson or Powell. Through advanced DNA testing techniques, it has been discovered Benjaman likely has a connection to the region.

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Maybe someone should sing some Appalachian folk songs and see if he
remembers them?? What cultural memories might be found with someone
who has lived in "eastern Tennessee, northern Georgia and western North Carolina" ?