TORONTO—It’s not every screenwriter who could succeed in writing a comedy about her own precarious and chaotic childhood, but then, Maya Forbes isn’t just any writer. She’s a Hollywood veteran whose credits include The Larry Sanders Show and Monsters vs. Aliens, which Forbes wrote with her husband, Wally Wolodarsky. He also takes a producer credit on Forbes’s debut as a director, the autobiographical Infinitely Polar Bear, opening Friday (July 3).

“I didn’t want to tell a woe-is-me story, because I didn’t have that much woe,” she explained in a one-on-one interview with the Straight at the Toronto International Film Festival last fall. “My father had a tough road, and my mother too, but also my sister and I were such little brats, and there was a lot of humour in my family. So I don’t feel that precious about it. Also, um, that’s boring.”

Instead, she “wanted to tell a story about everyday life, because those details are the most interesting things to me”.

“Have you seen this book called My Struggle [by Norwegian novelist Karl Ove Knausgård]?” she asked. “Six large volumes about his daily life, on the New York Times bestseller list. I like that. I haven’t read them yet, but I want to.”

Fair enough. James Joyce wrote Ulysses about one day in the life of an ordinary man. Literary embellishment on quotidian struggles is nothing new. It doesn’t hurt, either, that Forbes’s life story is hardly tragic. Played by Mark Ruffalo, the bipolar dad is a lovable misfit at worst.

“It’s interesting, because lovable is a word that I struggled with a lot,” said Forbes. “At first I tried to write a palatable version [of my life] that everyone would understand, and then I thought, ‘This is so boring and crappy.’ ”

Forbes cites older movies like Kramer vs. Kramer and Terms of Endearment, as well as François Truffaut and Mike Leigh, as influences. Did her 15 years in the business help or hinder her when she actually sat down to write her own movie?

“I had to work to eradicate them from my writing process,” she admitted. “In Hollywood, scriptwriters have this shorthand about how to depict vulnerability. They show the character patting a dog, for example.”

She also struggled with the amount of veracity and complexity from her own life that could be translated to the screen.

“I would think, ‘I’ll have the parents be divorced, because everyone understands that,’ ” she recalled. “But they’re not divorced, they’re separated. They’re in a grey area. And I decided to go with that grey area, to develop the characters slowly and not to worry so much about keeping them ‘likable’. Will Dad pull it together? Does he want to pull it together? Does Mom want him to pull it together? Sure, she wants their lives to work, but she’s scared, and everything is uncertain. It’s messy, like life. That’s the truth, so I decided to use truth as a guide.”