IÂ´m not sure as to where your grandfatherÂ´s branch would fit in in the Kean family history but according to Dunkling, the man who did the research on the Kean (Irish) familys, all Keans are related.
WeÂ´ll send you more information if we come across anything new.
Marshall and Elfriede Kean
This information comes from, "Book of Irish Names", Sterling Publishing Co., Inc. New York
Keane Ã“ Cathain
The Keane/Kane family were originally Mac Cathain of West Clare, Ã“ Cahain of Ulster and Ã“ CÃ©in of Munster. In time their Anglicization as Keane, Kane, made their topographical origins difficult to define. Their name derives from the personal name Cian.
Blosky O Kane, who slew the heir to the throne in the 12th century, was the forefather of the MacCloskeys, Aibhne Ã“ CathÃ¡in's descendants became the Mc Evinneys.
The Kanes tend to be numerous in Ulster while the Keanes are usually to be found in Munster and Connacht (Ireland).
For centuries, both at home and far afield, the Kanes/Keanes were active military men. In the 18th century there were 14 O Keane brothers serving in Europe.
In the 19th century, Kanes and Keanes were prominent in the sciences, architecture and the arts. The great acting family of Edmund Kean and his son Charles had their origins in Waterford. The popular playwright-publican, John B. Keane, is a Kerryman.
John Keane and James Keane, at different periods, were two of many Irish-Americans who filled the post of Bishop of Dubuque in Iowa, USA.
Cian (m) "ancient", An early Irish name which is still in use today. Kian and Kean are variants. It was occasionally anglicized as Cain.
Cain (m) Hebrew, "smith". The name was used to anglicize Cian, though why the name of such an unedifying Biblical character should have been chosen is something of a mystery. The use of this name is not confined to Ireland. Dunkling notes that he has traced 6 bearers of it.
"Book of IRISH NAMES", Sterling Publishing Co., Inc. New York