I guess I'd have to say word of mouth. My aunt did research on the family in the 60's and 70's. This is a quote from her page of sources:
"Several grandchildren of Frances
Hildebrand (Viva
Cox, Jacob Cook, and Frances
Huffman) said at various times that her father was Henry
Husselton and that she had a brother named John......."
I only started on genealogy recently, and don't know if this has ever been verified.