Marian Quinn was born in 1964 in Chicago, Illinois, the youngest child and only daughter in a family of five children. Her parents, Michael and Teresa Quinn met through family connections. Both were born and raised in County Offaly Ireland. They married in 1956. Her parents migrated from Ireland to Canada, then to London, England before settling in Chicago where her father, an English literature professor, taught at Loyola University.

Wanting to avoid what they perceived to be the insular Irish community on the south side of Chicago, Quinn’s parents decided to settle on the north side. Acquiring another teaching position at a community college, her father then moved Quinn and the rest of the family to Rockford, Illinois in the late 1960s/early 1970s. In this suburb of Chicago, Quinn and her family felt somewhat displaced and alienated.

In 1977, at age thirteen, Quinn moved to Ireland and lived with relatives; she remained there for five years, each summer traveling back to the United States to visit her family. For her secondary education, Quinn attended one of the schools in Ireland ran by the religious order, Poor Servants of the Mother of God. After Poor Servants, Quinn studied English at University of College Dublin for a short time.

Quinn returned to Chicago and studied acting at the Piven Theatre Workshop, following in the footsteps of her brothers, Aidan and Paul, who attended the workshop as well. In the 1990s, Quinn settled in New York, acting off–Broadway in plays such as Mike Leigh’s Ecstasy while at the same time, doing bit parts and minor roles in television (Law & Order) and film (Broken Harvest, Heavy). Frustrated and fed up with the lack of substantial roles, Quinn began to write, a passion of hers since childhood. Creative writing eventually led Quinn to develop her own screenplays, and ultimately direct, acquiring the creative independence she always wanted. In 1998, Quinn learned the mechanics and grammar of filmmaking while shooting Come To, a short film shot from the perspective of a hospitalized woman. In 2007, Quinn directed her first feature–length film, 32A – a coming–to–age story set in 1970s Dublin in which a thirteen-year-old girl receives her first bra and falls in love for the first time.

Quinn belongs to a family of actors and filmmakers that includes Aidan, recognizable from Desperately Seeking Susan, Benny and Joon, and most recently, the Prime Suspect television series (2011). Along with This is My Father, Paul Quinn directed Never Get Outta the Boat, and has several projects in development. An esteemed cinematographer, Declan Quinn has photographed a wealth of films including Vanya on 42nd Street, Monsoon Wedding, and Rachel Getting Married.

Quinn currently lives with her family in Ireland. Collaborating with producer and husband, Tommy Weir, Quinn has several projects in development for Janey Pictures, their production company.