If you want a lesson on modern Scottish identity, look no further than Ioanna Anderson. The 38-year-old playwright is a walking embodiment of 21st-century multiculturalism.

The first clue is in her name: Anderson is from her Irish father; Ioanna (pronounced Yo-anna) is from her Greek mother. The cultural cross-currents don't stop there. Having spent her childhood in Edinburgh, where she was expelled from school for spending too much time in the cinema, she headed to Dublin's Trinity College - the only place that didn't care about her references - to study English.

After a short stint in London, she settled in Dublin, working as an administrator for a number of small-scale theatre companies. When one of those companies, Greenlight Productions, was looking for a new play, she was in the right place to turn her hand to writing a monologue, so beginning a second career as a dramatist. One critic described Words of Advice for Young People, her debut with Rough Magic theatre company, as an "auspicious introduction of a writer with a great deal to say and exceptional skills with which to say it".

All of which means, 20 years on, Anderson is routinely described as an Irish playwright. "Because I started writing in Ireland, I mysteriously became an Irish writer," she says in an accent that carries echoes of Edinburgh and Dublin. "I was writing for Irish voices and I'd lived there for quite a long time and so everyone called me an Irish writer. I was like, No, I'm from Scotland', but it's too complicated to explain."

Things don't get any easier now she's making her Scottish debut at Glasgow's Tron Theatre while plotting the move "home" to Edinburgh with her husband and 18-month-old daughter. She'd blithely assumed Six Acts of Love was the kind of play that could take place anywhere, but as soon as director Andy Arnold put it in front of a cast of talented Scottish actors - including Una McLean - it became clear how much of an Irish play she'd written.

"Andy Arnold and I decided it was a universal play with universal themes and there'd be no problem transposing it to Scotland," she says on a flying visit to Glasgow. "Then we went away and phoned each other and, in the same breath said, Actually, it's not going to work.' There are specific times that created these characters. There are versions of them over here, but you would have had to change some key points to make it fit - and still people would be trying to identify exactly where they came from. It's more specific than I thought, so, yes, for a while I was an Irish writer."

Written for Dublin's Abbey Theatre during an unhappy time when more plays were being workshopped than staged, Six Acts of Love was like a "play going round and round on an airport conveyor belt" with nobody claiming it as their own, until Arnold seized on it as the perfect way to launch his inaugural season as artistic director of the Tron. It's a bitter-sweet comedy about a woman deserted by her husband and saddled with a mother losing her mind.

As well as the subconsciously Irish rhythms, the play's Irishness is most apparent in the true-life story that inspired it. "My mother- in-law had a great story about a friend of hers who had to do a peculiarly Irish thing," she says. "To get a divorce, she discovered she was never legally married. Although bizarre, it has happened to many people in Ireland. When they got married in the Catholic church, there was no registry office and they had to sign a civil document. A lot of the time it wasn't produced - the priest would forget. Divorce was only made legal in 1995 and then it was discovered that the documentation didn't exist. To get divorced, they had to go to the same priest with the same witnesses and re-enact the original marriage. It is peculiarly Catholic and of the moment."

The opening of Six Acts of Love coincides with You Are Here, a site-specific play she's written to be performed in an apartment in the Dublin Theatre Festival. If she times it right she can just see the first nights in both cities. All of which will be a good starting point as she makes the move back to her native Scotland and establishes herself as a bona fide Scottish playwright.

"I am actually writing a play for Scottish actors," she says. "That's been interesting. You have to come home and listen to people's voices and read the paper again. Scotland is at a totally different moment to when I left; politically, socially, everything has changed. It's a very dynamic moment here, which I hope to gatecrash." Six Acts of Love, Tron Theatre, Glasgow, tomorrow to October 11.