Sam's mother is English actress Emily Mortimer. Emily first made her mark as a stage actress after obtaining her degree from the University of Oxford. She began making appearances in movies and TV in her native England before moving to Hollywood, achieving her big break in 2000 with the film Love's Labour's Lost followed by Lovely and Amazing in 2001, which won her an Independent Spirit Award. Emily achieved greater fame with her leading turn in the HBO series The Newsroom from 2012-14 and the 2021 miniseries The Pursuit of Love, which earned her a BAFTA nod. Her other prominent roles include Howl's Moving Castle (2004), the Pink Panther franchise, Lars and the Real Girl (2007), Shutter Island (2010), and Mary Poppins Returns (2018).