Her father�s a 1970s legend, her mother a folk heroine and her brother a gay icon... cover star Martha Wainwright has fame in her genes. Interview by Alan Morrison.

IT has just gone noon in Saskatoon, Saskatchewan, and Martha Wainwright has a determined grip on her coffee cup, hoping for heat as much as a caffeine kick to start her day. Outside the tour bus, the Canadian town's main street is, as the singer less than delicately puts it, "as cold as a witch's tit". As weather goes, it's a far cry from the last stage of Wainwright's extensive world tour in support of her 2008 album, I Know You're Married But I've Got Feelings Too. "We just came from Australia," she tells me, "but for the Canadian leg, we've had to pull on our long johns and all of our woollies."

Before Canada and Australia came dates in Scotland and Ireland, taking her from the lands of Celtic origin to the wider spread of the Celtic diaspora. In this way, these recent months have been a good preparation for her upcoming gig in Glasgow as part of this year's Celtic Connections festival. The daughter of Canadian musician Kate McGarrigle and American singer-songwriter Loudon Wainwright III, she doesn't really consider her own brand of music to fall under any particular Celtic banner, although this tour has reminded her of the cultural heritage that has always surrounded her.

"There's a common interest in the old world, especially in Canada," she agrees. "I grew up in Ontario, where people have Highland Games constantly. In Newfoundland, people still speak with a strong Scottish and Irish accent, and their syntax is different too. It's a huge part of Canadian culture."

A constant reminder of those roots is her mother, whose surname hints at ancestors in Donegal. McGarrigle joined Wainwright on the Edinburgh date of the tour last October, and stuck with her daughter through gigs in England and Ireland. And it's not just in the professional capacity as a guest musician that mum makes her mark.

"It's necessary because otherwise we wouldn't see each other for more than three months," Wainwright explains. "It's family time and a time for Kate to take care of us. You get tired on the road, and having your mother around is really helpful. Not only can we put her to work - and the audiences love that, because she's a great musician - but we can also get her to make us cups of tea and fold our clothes." She starts to laugh. "With me as the daughter, I have a time limit on how long I can stand it. As I get older my mother becomes more and more important to me, but she starts to get on my nerves after two weeks. Then I just send her home."

It's doubtful if Wainwright's dad would even last that long. Theirs has been a strained relationship ever since her parents divorced when she was one year old and her singer brother Rufus was three. Father and daughter have made public their feelings in lyrics - Martha famously included a track called Bloody Mother F***ing Asshole on her debut album and has criticised Loudon for writing songs about his children rather than helping raise them. But at other times they've patched things up to the extent that they could collaborate on the track You Never Phone on his 2003 live album So Damn Happy. As our conversation continues, though, it's clear that it's McGarrigle who was - and remains - Martha's guiding force both personally and musically.

"My mother and my aunt Kate's singing partner, Anna McGarrigle are huge influences on me," she admits. "When I was growing up, there was a lot of Celtic music and English music, things like The Incredible String Band and records by Aly Bain. And Ewan MacColl - my favourite song is The First Time Ever I Saw Your Face. Kate and Anna are obviously influenced by a certain amount of Irish music because they're from Quebec, where you can hear it in the music, in the button accordions and fiddle. They were also interested in forging their own paths, however, so it wasn't heavily emphasised. But it was clear where the roots lay."

It's tempting to think of those childhood years in their Canadian home, particularly at Christmas, as something from a modern-day Frank Capra movie, as the kids and extended family nuzzled closer to an open fire, picking up instruments and beginning a communal singalong. This image has probably been boosted by the release of the collaborative McGarrigle Christmas Hour album in 2005, which saw Martha, Rufus, Kate and Anna joined by the likes of Emmylou Harris for O Little Town Of Bethlehem and some less familiar yuletide songs. It also transferred into a live format, with concerts such as the one held at New York's prestigious Carnegie Hall last December. But this nostalgic portrait isn't quite what Wainwright remembers as reality.

"It's funny because, in our family, there isn't a lot of jamming and session stuff or people playing together," she says. "That probably happened a lot more with Kate and Anna when they were younger, so I think with Rufus and I there's been not a struggle, but an insistence on having our own voice. But playing together became very much an excuse for us to spend time together because we're on the road so much of the time. The music has become a job, but within that job we found a way to make it also about family. So it's kind of come full circle in many ways.

"And so the McGarrigle Christmas Hour record - I'm sure my mother came up with the idea because it's the kind of thing she would do - was really about spending time together. Of course, at Christmas we had to learn carols. It's really f***ing cold in Quebec and you don't leave the house, so instead of carolling door to door we always carolled in the living room. My mother's favourite thing was to find difficult things for us to sing, things that were not that well known, with four or five-part harmonies and an odd religious slant to them. It wasn't about sitting around singing Jingle Bells; it was really about trying to read sheet music and come up with an eerie, beautiful Christmas sound."

Wainwright got early exposure while singing backing vocals for her more famous brother before finally releasing her eponymous debut album in 2005. It had folky touches, particularly on her cover of Whither I Must Wander (music by Ralph Vaughan Williams, lyrics by Scotland's Robert Louis Stevenson), but also an acoustic, singer-songwriter, café vibe. If her sound can be said to have found a poppier edge on I Know You're Married that might be partly the influence of her bassist-keyboardist-producer (and, since September 2007, husband) Brad Albetta.

While the emotional benefits of having your partner as a member of your band are obvious, one wonders what Albetta made not only of touring as an extended honeymoon, but of having his mother-in-law along for regular parts of the ride.

"Well, the honeymoon is over," Wainwright laughs. "I say that jokingly, but to be honest, it's even better to have Brad with me because it would be really hard to maintain a relationship and a marriage if you couldn't be together for really long stretches. I mean, I know people do it in the military or whatever. But, with him here, it's much easier to find a restaurant on our day off, or go to a museum, or sit around and watch TV when you have an hour and you're exhausted. I'm really lucky to be able to do that with the people I love."

Another of her professional-personal, musical-emotional entourage is Teddy Thompson, who will take the support slot at Wainwright's Celtic Connection gig. They've been close friends since they met through Rufus in Los Angeles a decade ago, and have regularly toured and recorded together. As the son of folk legends Richard and Linda Thompson, Teddy has a keener understanding than most of the pressures put on Wainwright's shoulders when trying to forge an independent solo career.

"I don't want to say it's an uphill battle because obviously Teddy, Rufus and I were given a lot of opportunities that not many other people would have," she explains. "But you get exhausted always having to talk about your parents in interviews. There's a benefit to that, but there's also a feeling of wanting to break away. So he's a very close friend, and we've played together, literally and metaphorically, for years."

Although Wainwright's solo material hasn't yet tickled the top end of the UK charts, she shared a top 20 hit late in 2006 as guest vocalist on Snow Patrol's single Set The Fire To The Third Bar (from their Eyes Open album). While deflecting any suggestion that she might have stolen some of Gary Lightbody's audience to add to her own following, she does seem to have genuinely enjoyed the experience ("I didn't really have any idea how famous they were, I just really enjoyed the song and got a kick out of singing it a few times at the festivals in front of 50,000 people").

The Snow Patrol collaboration is one example of how Wainwright has deliberately set out to underline her versatility - and perhaps to distinguish herself from her parents and brother. During her first solo tour, she performed a handful of tremendously evocative chansons, and lets slip to me that she is currently starting a side project on Edith Piaf and French songs. In April 2007, she also took to the stage at Covent Garden for a production of Kurt Weill and Bertolt Brecht's "sung ballet" The Seven Deadly Sins.

"People in the music industry are interested in creating a look and persona that is consistent, because it doesn't confuse an audience," she explains. "And I've really fought against that because it's not in my personality to fit into any one sort of style, even in the way I dress or in my tastes. I have antennae for the past and the present and the future."

The Seven Deadly Sins shows were a particular treat for her. "It makes sense because you don't have to be an opera singer to sing Kurt Weill. But what really excited me about that project was to be on stage with the Royal Ballet. As a girl who did ballet until she was 12, being on stage with ballerinas at Covent Garden, then getting married soon afterwards, it was a girl's dream come true. It's like, all I need is a pony and everything will be accomplished."

Joking aside, Wainwright clearly won over the Covent Garden bigwigs, because The Seven Deadly Sins is being revived for a further six performances at the end of this month and into February.

The apparent ease with which she has ingratiated herself among the highbrows of the Royal Opera House might come as a surprise to fans who remember the party animal reputation she had only a few years ago. Perhaps this means she was no stranger to the subject matter of Weill's music and Brecht's lyrics. If so, which deadly sin was her closest companion?

"Probably gluttony," she admits. "Especially when you're out there with the dancers, and they're extremely thin, and you're feeling like eating a million sandwiches. I don't think that's the worst of the sins but I enjoy life. With singers, there's a gluttonous element to our lives."

Perhaps Wainwright will be able to burn off that excess when she comes back to Scotland. Although her concert is in Glasgow, she might find time to travel through to Edinburgh and climb Arthur's Seat, something she has done every time she has played the Scottish capital.

"Anything you can repeat on tour is nice," she says, looking out at Saskatoon and still hugging that coffee cup for any lingering trace of warmth. "We mostly play in cities, so we're never in the country. It's not that Arthur's Seat is in the country, but it looks like it is." She sighs. "It's sad, really - a bunch of Americans and Canadians trying to live out an afternoon of some sort of Celtic bliss..."

Family tiesRUFUS WAINWRIGHT
Relationship: brother
Although born in New York, Rufus grew up in Montreal and studied piano there at McGill University. He released his debut, self-titled album in 1998, and was subsequently named Rolling Stone's best new artist of the year. Despite a period of addiction to crystal meth, he has released four other albums, performed Judy Garland's entire Carnegie Hall concert live, and has written an opera called Prima Donna.

Martha on Rufus: "Rufus and I are very different. I think he's a lot more dramatic and romantic with his songwriting ... My songs are steeped in an earthiness, and I feel more of a struggle to be understood. I sort of see Rufus's career in music as being written in the stars, whereas my career came up from the roots in a more arduous way."

Album choice: Release The Stars (2007) Song choice: Agnus Dei (on Want Two, 2004)

LOUDON WAINWRIGHT III
Relationship: father
Born in North Carolina in 1946, Loudon played folk clubs at the tail end of the 1960s before releasing his first album in 1970 and establishing a style that combines wryly humorous lyrics with roots-soaked tunes. He has also dabbled in acting, taking small parts in movies and, in the mid-1970s, a recurring role in TV series M*A*S*H; he was also resident singer on Jasper Carrot's comedy show Carrot Confidential in the late 1980s. He and Kate McGarrigle divorced in 1977.

Martha on Loudon: "For most of my childhood, Loudon talked to me in song, which is a bit of a shitty thing to do. Especially as he always makes himself come across as funny and charming while the rest of us seem like whining victims, and we can't tell our side of the story."

Album choice: I'm Alright (1985) Song choice: Pretty Good Day (on Social Studies, 1999)

KATE McGARRIGLE
Relationship: mother
A native of Quebec, she and her sister Anna first performed together professionally as part of Canadian folk group Mountain City Four in the 1960s. As a duo, they released their first album in 1975 and have recorded a handful of collections in French, as well as writing their own songs and covering folk standards. Kate was invested into the Order of Canada in 1994.

Martha on Kate: "She is someone who never gave up on me as a singer or songwriter, even when maybe she had reason to.''

Album choice: The McGarrigle Hour (1998) Song choice: Kiss And Say Goodbye (on Kate And Anna McGarrigle, 1976)BRAD ALBETTA
Relationship: husband
Mostly based in New York, producer Brad worked on Martha's debut album, playing bass and keyboards as well as twiddling knobs in the editing booth. He has also worked with Teddy Thompson, Rufus Wainwright, and The Sad Little Stars. He and Martha married in September 2007.

Martha on Brad:
"I fancied him, so I kept him around as much as I could. He's obviously a very patient and strong person, to be with someone like me. I think he's taken a lot on."

Album choice: Separate Ways by Teddy Thompson (producer, 2005) Song choice: Bloody Mother F***ing Asshole (bassist, on Martha Wainwright, 2005)

Martha Wainwright plays the Old Fruitmarket, Glasgow on January 27.