George Clooney is Irish. The Clooney clan is from Ireland but it also migrated to Scotland and became a Scottish clan. Just like the Kennedy clan.
The Irish have long mixed with Scots, Welsh and English. Irish clans are not just local Irish clans but also Scots, Welsh and English clans.
Similarly, the Scots have long mixed with Irish, Welsh and English. Scottish clans are not just local Scottish clans but also Irish, Welsh and English clans.