It is fascinating to hear Aiden McGeady's decisions for choosing the Republic of Ireland over Scotland in international football.

As next week's Euro 2016 qualifier between the two countries looms in Glasgow, and McGeady's abuse from some fans is guaranteed, the least we can do is give 10 minutes to his own testimony.

McGeady, like many with emigrant roots, such as the Irish-Americans or the Scots-Canadians, grew up steeped in the cultural ways of his forebears. Born in Glasgow, and to a Scottish father, McGeady spent most summers of his youth in Ireland, where his paternal grandmother lived. By the age of 13, the winger has said, he felt infused with Ireland and loved the country of his ancestors.

There is family footage of McGeady at the age of 10 playing keepy-uppy outside his house - and he is wearing an Ireland top. Being an unknown little kid at the time, this cannot possibly have been any sort of affectation. Simply, under the influence of his father and grandmother, McGeady came to feel an affinity with Ireland, and to love and respect the country.

There was a short film of McGeady's experience in choosing Ireland over Scotland, made in Ireland about seven years ago while the player was still at Celtic, in which McGeady's father, John, whose parents came from Donegal, explained his son's gradual evolution towards an Irish identity.

"Aiden's decision to play for Ireland was based on a very rich heritage of Irish culture, passed down from father to son and from aunts and uncles, and he spent every single summer as a child in Ireland, just as I did," said John McGeady. "So he was very much ensconced in the Irish way of life and had a real respect and love for Ireland. This was why Aiden made the decision to play for Ireland."

In all of this the role of John McGeady cannot be played down. In all things Irish, John heavily shaped his son's outlook on life and Aiden warmly embraced his father's world view. So a father and a son, through football and much else, forged a bond and a sense of identity based on their family's historic roots.

"Everyone used to ask me when I was younger, 'will you play for Scotland or Ireland?' and for some reason I'd always say Ireland," said Aiden, now playing his club football at Everton. "I used to go over there every summer as a kid to stay with my gran and I grew up with fond memories of Ireland. I always enjoyed being there."

In fact, there is a bit more to McGeady's fate in playing for Ireland than just this. While he was still a schoolboy a compound of circumstances, whereby Celtic would not allow him to play schools football and the Scottish Schools FA only chose those who played for their schools, meant that McGeady went overlooked by the SFA until he was around 17 years old.

By this point, via Pat Bonner, the former Celtic goalkeeper, Ireland had clasped McGeady for their own youth teams, and McGeady loved it. His fate was sealed and it was a fate he desired.

So we come to this: next Friday night in Glasgow, when Scotland face Ireland, McGeady is guaranteed to be booed by thousands of Scots. Some will shout "traitor" at him, while other poor souls will produce more poisonous splenetic outbursts.

In all this it is worth pointing out one essential of football: no-one ever seriously suggested constructing a rule headlined: "Booing To Be Banned". Who could possibly take such a thing seriously? The day they ban booing or barracking from football grounds will be the day many of us walk away. Supporters' outbursts are germane to the game.

For those who feel deeply that McGeady should be playing for Scotland - the land of his birth - why shouldn't they josh or barrack him? Is this a game of chess in an art-gallery we are about to watch? For heaven's sake, this is football, and Scottish football at that. When did anyone ever expect prissy decorum?

But many know another problem here. Booing McGeady for "turning his back on Scotland" - which, by the way, he has done - is one thing. Bigoted abuse, however, is something else. I've seen enough online, and witnessed enough in the flesh, to know that more than a few football fans in the west of Scotland view McGeady as "that wee Fenian" who needs sorting out.

I'm not sure what more there is to say about this. As surely as it freezes in winter, bigotry in Scottish football persists. McGeady knows all about it from his time with Celtic and is ready for it. (He might even revel in it, in the sense that it helps to raise his game). The plain fact is there are those who will not just resent McGeady at Celtic Park on Friday night, but who will deeply and irrationally detest him.

The same will apply to James McCarthy, should he be selected by Martin O'Neill, the Ireland manager. McCarthy's, like McGeady's, is a story sort of half-told and half-understood. But the crude synopsis of it says he turned his back on Scotland.

It seems international football fans can love or deplore an 'adopted national' depending on when it suits them. I remember one Portuguese fan at Euro 2004 explaining to me how much they all loved Deco, a Brazilian. So those Scotland fans who will barrack McGeady had no problem at all in an Englishman, Stuart McCall, playing so vibrantly for Scotland.

James Morrison, who is as English as a pint of bitter, is one of Scotland's most valued players right now. The fact that Morrison's link to Scotland, like McGeady's to Ireland, extends back to a grandparent appears not to trouble the Tartan Army one jot.

The confirmed rule here is there is selective outrage. And, in McGeady's case, there is that extra spice, provided by the west of Scotland, of anti-Irish racism or religious bigotry. Of the latter, there is little point in probing further. It is there, it prevails, and it seems there is little anyone can do about it.

McGeady says he feels a lot of Ireland inside him. I, for one, don't feel qualified to say to him, "no, Aiden, you don't, so be quiet". McGeady now has over 70 caps for Ireland and is still just 28.

What that great country, Ireland, has gained, another great country, Scotland, has lost.