The series — which follows a mentally ill man named Thomas and his identical twin brother Dominick (both played by Mark Ruffalo), who protects and cares for him no matter the sacrifice — is one of Ruffalo’s best performances yet. Both brothers are portrayed by the endlessly talented Ruffalo, who lost 20 pounds to play Dominick and gained 30 pounds to play Thomas. Since the story feels so real and handles subject matters like paranoid schizophrenia and unconditional, painful love with such nuance, it might make viewers think I Know This Much Is True is based on a true story. Even though the series is very realistic with its portrayal of mental illness and complex relationships, the story is actually a work of fiction. But that doesn’t mean I Know This Much Is True doesn’t come from very real experiences.
I Know This Much Is True is based on Wally Lamb’s bestselling novel of the same title which was published in 1998. Although Lamb writes about the novel’s subject matter incredibly convincingly, I Know This Much Is True isn’t based on his own experiences, although a few elements from his life made their way into his storytelling. For instance, like the twin brothers, Lamb also comes from a Catholic Italian family. Additionally, in an interview, Lamb shared that his hometown (Norwich, Connecticut) had the largest state hospital for the mentally ill and this “scared and fascinated” the author when he was younger. So, creating a character who is forced to seek help from a mental health facility seems to have been drawn from Lamb’s past surroundings and interests.
As for Ruffalo, the person who brings Thomas and Dominick to life, he shares that he related to his characters in a monumental way. In 2008, Ruffalo’s brother, Scott, was tragically murdered, and this devastated the Marvel actor, with whom he was very close.
Ruffalo told GQ, “I knew the depth of a relationship between two brothers — me and my brother were what they call ‘Italian twins.’ We were barely a year apart. Family and siblings were always being pounded into us: ‘Your blood is thicker than water, don’t let that person come between us, your friends are temporary, your family is forever.’”
He also added, “[Series director Derek Cianfrance and I] talk a lot about my brother because Dominick and Thomas’s relationship isn’t very different from ours. Not directly, but in an abstract way: that kind of caring, that kind of messiness, that kind of conflict, that kind of jealousy. All these things that are messy about being a human being all come out in family relationships.”
Just because a story isn’t based on true events doesn’t make it any less moving or meaningful, and many will find that I Know This Much Is True successfully captures humanity in its most vulnerable, volatile form. What you feel when you watch it is very real.