You and I have corresponded before. I believe that my husband is descended from this line. His furthest ancestor is Isaac Jefferson born 1792 in Delaware. The best guess is that his dad is Richard IV since he named his oldest son Richard.
Isaac moved to Kentucky and then to Missouri. My husband has done the Family Tree DNA thing. We are currently trying an experiment for my son's science fair project on changes in the Jefferson Y DNA by testing the male Jefferson members of his family.