Check out this definition (all you contentious people) that I found at another website. You could have some good go-rounds with the person who wrote this:
How Irish is Traditional Music?
It is Irish by virtue of its being played in the island called Ireland.
There is a general feel to this music which distinguishes it from the traditional music of, say, Scotland, or the Eastern United States. But there are many similarities between Irish traditional music and the traditional music of Scotland and the Eastern United States.

There are many differences within Irish traditional music: the music of West Cork is different from the music of Donegal. Perhaps we can see them as dialects of a language: a musician from Donegal will find it difficult to play with a musician from West Cork; he might find it equally difficult to understand his accent.

One of the features of traditional music is its capacity for absorption, retention and change. Traditional music has always drawn on many influences and sources: for example, the ballroom schottisches and polkas of polite 19th-century society, English music-hall songs, Scottish bagpipe music, and even the music of visiting blackface minstrel troupes. The trend continues to the present day - there is a current fashion for making traditional dance tunes from such commonplace material as the theme tune from "Dallas". The traditional group De Danann have made a hornpipe from the Beatles' song 'Hey Jude'. Whether or not these tunes survive in the future will be determined by the community, in this case the other traditional musicians and their audience.

In this context, 'Irish' means absorbing other influences and making them feel at home.

Whaddya think?