Rooney Mara was born on April 17, 1985 and was raised in Bedford, New York, a town in Westchester County Mara’s mother’s family founded the Pittsburgh Steelers and her father’s family founded the New York Giants. Her father, Timothy Christopher Mara, is the vice president of player evaluation for the New York Giants, and her mother, Kathleen McNulty (née Rooney), a part-time real estate agent. She is the third of four children: she has an older brother, Daniel, an older sister who is also an actress, Kate, and a younger brother, Conor.

Mara’s father has Irish, German, and French-Canadian ancestry, and her mother is of Irish and Italian descent. Her Rooney ancestors originated in Newry, County Down. Her paternal grandparents are Wellington Mara and Ann Mara. Wellington was the long-time co-owner of the Giants, who was succeeded in that position by her uncle, John Mara. Her maternal grandfather, Timothy James “Tim” Rooney, has run Yonkers Raceway in Yonkers, New York since 1972. Mara is the great-granddaughter of both New York Giants founder Tim Mara and Pittsburgh Steelers founder Art Rooney, Sr., as well as of Kathleen McNulty Rooney. Her great-uncle, Dan Rooney, is chairman of the Steelers, the former United States Ambassador to Ireland, and the co-founder of The Ireland Funds charitable organization. U.S. Rep. Tom Rooney from Florida is her first cousin, once removed.

After graduating from Fox Lane High School in 2003, she went to Ecuador, Peru and Bolivia in South America for four months as part of the Traveling School, an open learning environment. She attended George Washington University for a year and then transferred to New York University’s Gallatin School of Individualized Study, where she studied psychology, international social policy and nonprofits, graduating in 2010.

Mara was inspired to act by seeing musical theatre and classic movies, like Gone with the Wind (1939), Rebecca (1940), and Bringing Up Baby (1938), with her mother. She also wanted to be like her sister, Kate Mara, a professional actress. Patricia resisted pursuing acting as a child, stating to The Journal News that “it never seemed that honorable to me, and I guess I was always afraid that I might fail.” Her first and only role in high school was Juliet in Romeo and Juliet, which she got after being signed up to audition by a friend. Mara acted in a few student films while at NYU, and then began her career in acting, first auditioning at the age of nineteen.