As I’m waiting to be connected to Molly Rankin of the Canadian indie-pop band Alvvays, the video for one of their new tracks In Undertow – an addictive shoegazey swirl of Farfisa and feedback – has just gone live on YouTube. When she comes on the line from Toronto, I ask if she’s watching real-time reactions on the comments thread.

“I learned very early on that it’s not good to read that stuff,” Rankin says cheerfully. “I’ll probably go for a long walk for a few hours today and then come back and see if there’s been any disaster.” I read a few of the responses out nonetheless: “This is fricking amazing”; “Totally 80s and totally awesome”; “Molly so cute.” YouTube’s little thumbs-up icon has already been clicked hundreds of times. “Things are always good early on,” Rankin deadpans.

The Alvvays singer, guitarist and songwriter isn’t exactly a paragon of self-assurance, but she has every reason to feel upbeat as they prepare to release their second album, Antisocialites. The making of their self-titled debut album was long and precarious – Rankin had to pay for it to be mastered with waitressing money – and it took time to find its way into people’s affections after cassette copies were tentatively circulated, eventually getting a full release in 2014. Thanks to intoxicating, swooning songs such as Archie, Marry Me, the album made several critics’ end-of-year lists and sent Alvvays out touring the world for two years solid.

Molly Rankin of Alvvays.

Antisocialites is a jangling bubblegum riot recalling Scottish indie-pop like the Vaselines and Camera Obscura. Rankin has a voice so sweet and yearning she could sing you a prison sentence and still make it sound dreamy. Her steady blossoming as a songwriter is particularly admirable when you consider how a tragedy in Rankin’s youth could quite easily have turned her away from music forever.

All five members of the band hail from remote islands in northern Nova Scotia; Rankin is the daughter of John Morris Rankin, a fiddler with the Celtic folk family collective the Rankin Family. In the 1990s they sold 2m records, scooped armfuls of awards including six Junos and were credited with sparking a North American renaissance of Celtic music and culture. “It’s crazy – the places they resonated in are still revealing themselves to me,” says Molly of her father’s band’s successes, which all occurred while she was still very young. “People come up to me when we’re in Europe and talk to me about them. There was one guy who showed up at one of our shows with a binder full of pictures of my dad playing fiddle.”

Near dawn on a Sunday in January 2000, John Rankin was driving Molly’s older brother Michael and two of his friends to a hockey match when he skidded off the road, sending his truck plunging off a 75-foot high cliff into a cove. The teenagers managed to break a window and swim to safety. John Rankin didn’t make it back to shore alive. Molly was 12, and lost not only her father, but also, as a promising young fiddler herself, her mentor. “At the time of his passing I was really growing as a fiddle player, and afterwards there was this sign of life through me and through my playing that everyone noticed,” she recalls. “It was bringing everyone such hope in that time. But it was also a lot for me. I felt like I wasn’t at the stage where I had my own style; I was just trying to retrace his steps, and that became fairly exhausting.”

At 19, she has mastered the fiddle – “one of the hardest instruments” to play – sufficiently to perform a tribute to her father as part of a Rankin Family reunion tour in 2007. By then her musical interests were already shifting, particularly after she met Alec O’Hanley, with whom she is romantically and professionally involved. Now playing guitar alongside her in Alvvays, he switched her on to indie rock, including Teenage Fanclub, a band she describes as “a door”.

“Alec gave me, I think, two copies of Bandwagonesque – one for the car and one for the apartment,” she says. Rankin sent him demos of some songs she’d been working on. “He didn’t like them,” she says with a laugh. “He was the first person to say, ‘I think you can do better’.”

Their relationship has been rocky at times, and Rankin has gone as far to describe the new album as “a fantasy breakup arc”, where “life nearly imitated art”. “We’ve been sort of pulling each other over mountains for the last few years,” she admits.

She has also had to face down pressure put on her by people in the music industry, and herself, to be a more extroverted band leader, with the title Antisocialites nodding to Rankin’s resistance. “When we were starting out, there was some expectation that I would be a certain type of frontperson, that I would develop into someone very charismatic and comfortable – and that’s never really happened,” she explains. “But it’s not really the school I come from. I don’t like to really rock out on stage or have some kind of strange rock persona. Over time, I’ve learned that I’m allowed to be just this reserved, awkward human.”

Before leaving Rankin to her long walk, I have to ask: what would her father would have made of Alvvays?

“Something that he always instilled in me was that if you’re not going to do something 100% then don’t even bother. That is definitely in the back of my mind constantly. So I’m sure I would be an academic or something if he were still alive,” she laughs. “Or he would be there yelling, ‘Tune the guitar!’”