Actually, the Irish did have a lot to do with the development of the kilt: Irish weavers manufactured the tartan fabric in various patterns and colors meant to please the Scottish eye. Nowadays we have trade tartans for all kinds of groups, but in olden days the Irish might not have worn tartan but they certainly sold it. Google the Clodagh tartan for more details.

Every 3 or 4 years I put on my presentation for the local Irish Association called "The Irish VS. The Kilt" and I have a lot of fun with it. Kilts aren't truly native to Ireland but they can be "a Scottish expression of Irish identity".