just back from Ireland; it appears the family name origins date back to 1600 - a Dermot O'Kynnaghan or O'Kynaghan was a land owner, in Ballyowen, Offaly or Tipperary; subsequently a small town was named Ballykynaghan, with several name changes; there is still a place called Ballykeenaghan;
There probably was a large estate owned or held by a "Kinahan" in the mid 1700's on the Border of Offaly; this was twice removed from their hands by the British in the 1600's, and greatly reduced in size; by 1770 the oldest son held it, and the younger son, Daniel (b. 1756), made his way to Dublin to start the whiskey business; there is a well outlined family tree following him, as he became fairly well to do. Reverend John Kinahan of Knockbreda was his son, and applied for the coat of arms you all may be familiar with.
We met Daniel's GGG grandson, Danny Kinahan, in Belfast in Sept. Much work to do to re-establish the family tree!