“Always listen to your mother” isn’t exactly the kind of central tenet they teach you at Harvard Business School. But for Emily Sugihara, the California-raised, Brooklyn-based designer behind the reusable bag line Baggu, it’s a piece of advice that’s been invaluable to the brand’s runaway success since its founding in 2007. Back then Sugihara was a Parsons grad working as an assistant designer at J. Crew, just coming to realize that a corporate job wasn’t her calling. “As a kid, I was very entrepreneurial, and I always knew I wanted to have my own company,” she says. At home over Christmas break one year, Sugihara and her mother began talking about making a line of reusable shopping bags. Her mom was “sort of a treehugger” and an artist in her own right — an expert seamstress who learned to sew making her own clothes as a kid in rural Michigan — and Sugihara was a die-hard New Yorker-in-training, sporting fingers turned purple each week as she lugged home bags full of groceries. Together they came up with a bag that’s almost exactly like the original ripstop nylon Baggu that sells today: long handles that fit comfortably over the shoulder, gussets along the bottom that allow things like milk and eggs to stack, and a single, double-reinforced seam that’s the result, Sugihara says, of her mother’s “sewing genius.”