So, we have something in common with England after all, despite spending the last 800 years insisting we're night and day. Both countries are tripping over themselves to claim Daniel Day-Lewis as 'one of us'.
We can be touchy, narrow and judgmental about definitions of Irish identity, but we've suspended hostilities in Day-Lewis's case because he's arguably the most-gifted actor of his generation, and because we're vain (and still a little insecure) enough to be flattered that he wants to join our team.
In listing him as an Irish contender for an Academy Award for his role in 'There Will Be Blood', we're volunteering him to fly the tricolour. Meanwhile, the British have him waving the Union Jack -- with considerably more justification on paper, in fairness. But let's not overestimate the importance of technicalities.
Admittedly, we're highly selective when it comes to Day-Lewis, whose talent and celebrity would guarantee him a welcome anywhere he chose to settle. If he wants to say he's a Mick, that's fine by us.
There's less of a rush to acknowledge others who claim Irish ancestry or an affinity with the land. Ian Bailey for example, a suspect in the Sophie Toscan du Plantier murder, may have settled in west Cork, but there's no stampede to welcome him into the parlour.
Still, in recognising Day-Lewis as one of our own, we're signalling you don't have to be Irish to be Irish. That national identity is about more than genealogy or surname or the geographical location that appears on a birth certificate. It can also mean choosing to live somewhere and making an effort to belong there.
And that's a positive message to send to the multicultural, multiracial society that's in the process of developing here. Irish skin tones are turning black, brown and yellow -- they're no longer just freckled. I saw my first black face at 16 when I holidayed abroad. Fast forward a couple of decades and in some Dublin schools one-fifth of their pupils are from overseas.
Consequently, a reassessment of how we define national identity is overdue. For me, it's rooted in citizens who engage with society and are loyal to it -- more relevant characteristics today than listening to De Danaan CDs, going about in an Aran geansai, or being able to cite a relative who was inside the GPO in 1916.
No harm in any of the above, but they elevate no-one to a higher plane of Irishness.
The Nigerian-born Mayor of Portlaoise, Rotimi Adebari, has shown by his actions in entering civic life that he wants to make a contribution to his new homeland. He is an example of the new breed of Irishmen we may see develop, in time.
Conversely, it's possible to come from Irish stock and not be much of an Irishman: to treat nationality as an accident of birth and have no interest in your community. The native born can learn from the Adebaris who come here.
As for Day-Lewis, strictly speaking he is English, of Irish extraction. He grew up in London with an Irish father and an English mother; however, his father, Britain's Poet Laureate Cecil Day-Lewis, brought him on holiday to Ireland regularly and he developed a love for the country. He has a home in the Wicklow hills, holds an Irish passport and has dual British-Irish citizenship.
A sense of belonging can't be measured in terms of DNA. It has to be present in hearts, not molecules. Day-Lewis made an emotional choice to stand up and be counted -- and at a time, before the Good Friday Agreement, when wearing the green was less desirable on an international platform than it might be perceived today.
Is Irishness a state of mind, then, rather than ethnicity? Can you have an English accent -- or an American or Australian one -- and an Irish heart? I don't see why not, so long as you connect with the country.
But Irishness was traditionally more inclusive than we give it credit for nowadays: Parnell spoke with an English accent and loved cricket almost as much as Kitty O'Shea. Dev was born in New York of Cuban ancestry. Both were Irishmen.
Any modern definition of Irish identity has to embrace factors beyond genetic composition or place of birth. If we are blinkered and protectionist, we are storing up trouble.
Such a limited scenario means a host of social cohesion problems waiting to erupt via the Irish-born or Irish-educated children of asylum seekers and other immigrants.
Hopefully, they will feel they belong to the nation where they grew up, even if they also retain a natural affinity with the country of their origins. It's in everyone's interests to help them access that sense of belonging.
For a small nation, we get hugely exercised about what exactly comprises Irishness. Like the Lilliputians, who embarked on a holy crusade with their neighbours over which end a boiled egg should be cracked, we divide and subdivide each other mercilessly.
To Dubliners, everyone else is from the country, even if they come from another city. Northerners are different, despite imagining they blend in. Cork people are more different again.
It's a minefield. But the idea of Irishness has to be fluid.
As for Day-Lewis, he's a lot more Irish than Tony Cascarino ever was, despite kitting out in the green jersey.