Who were more likely cousins and we'll probably never know the answer.
I found a suggestion in a MyHeritage tree
https://books.google.com/books?id=reQZDgAAQBAJ&lpg=PA69&ots... page 145 of The Outlaws of Cave-in-Rock By Otto A. Rothert
Says that TS Smith in 1855, who interviewed eyewitnesses, asserted that Micajah was born William, son of John Harp, and his cousin Wiley was Joshua, son of John's brother Wiliiam.
Trying to pick through the notes in this file, it's hard to follow
http://www.genealogy.com/ftm/h/a/r/Dana-Harp/WEBSITE-0001/UHP-0579....
I was wondering if he was somehow related?
Oh Goody, he is my 6th cousin 4xs removed
https://www.geni.com/path/Jamey-Balester+is+related+to+Wyatt-Earp?f...
One more thing...Earp /Harp Connection
http://www.genealogywise.com/group/harpersurname/forum/topics/my-ha...
This link looks decent
http://www.genealogywise.com/m/group/discussion?id=3463583%3ATopic%...
Can we check the Geni tree against it?