Why Pop Duo Tegan and Sara Think Everyone Can Relate to Their New Memoir, 'High School'

Tegan Quin gets asked one question more than any other: Where’s Sara? It’s no different today at dinner, when her twin sister, bandmate and now cowriter on new memoir High School is still in her hotel room on a phone call.

“Nobody ever says to me, ‘Who produced this record?’ or ‘What’s your songwriting process?’ They always just say the same thing,” Tegan, half of pop duo Tegan and Sara, explains to PEOPLE. “That lends itself to all these other questions, like, Where do we fit into each other’s lives? It’s actually more interesting than we give it credit for — like, What do you do together?”

She saves a place at the table and orders dinner for Sara as she begins talking about writing their first book, which tells the story of their high school years in Canada leading up to the formation of their band. It’s out Tuesday alongside a new album of re-recorded songs from those years, Hey, I’m Just Like You, out Friday.

“We’re very interested in mining that part of our lives,” Tegan says. “That’s when we developed all of our skills. It’s when we developed our identity, it’s when we started to figure out who we were.”

Tegan and her sister are both gay, and much of the book is devoted to their first relationships as they separately discovered their sexualities. Narrated by the sisters in alternating chapters, the book is broken into three sections for grades 10, 11 and 12 (in Canada, grade 9 is part of junior high), with the summers as interludes. Other major themes include their parents’ divorce and their experiments with drugs, along with their early success in music.

When Sara arrives about a half-hour later, she says she’s sure Tegan explained “the true facts of what happened” beforehand. Shortly after, she adds her side of the story: She went to therapy because of the memories the book brought up for her.

“The truth is, I hadn’t really gone back and processed,” Sara says. “I hadn’t actually sat for days and days or weeks and weeks writing about my memories around my first homophobia experiences or what it felt like to be 15 years old and caught in a sexual relationship and have to lie to my mother, or to be ashamed of myself. I’d never put into words how much shame I’d been carrying around.”

Although she’s often asked when she came out to her sister, Sara later adds, “I still haven’t told her! I have never said to Tegan, ‘I’m gay.’ We didn’t talk about it! I couldn’t even tell my sister!”

Going to therapy was “helpful,” she says, and with the book now written, “the final outcome feels really good.”

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Sara doesn’t know if she would’ve read their book when she was in high school, she admits, and says the new album might be better for reaching high-schoolers. But Tegan thinks everyone can get something out of the book.

“It’s not like we wrote a memoir about climbing a mountain blindfolded upside-down — we wrote about being teenagers and falling in love. Like, who the f— hasn’t done that?” Tegan says. “We all go through this experience, whether you’re gay or straight, a guy or a girl, you live in rural wherever. Being a teenager can be really tough.”

Throughout dinner, Tegan has been distracted by two men doing high-intensity strength exercises. At the end of the meal, she notices them once again, and reflects: “It’d be amazing to be that strong.” Judging by their book, though, she and her sister already are.