Caulkett was born in Camden, London, England, UK, on 13 November 1913. She was raised in Kentish Town in London alongside her three brothers, David, George, and Stanley, as well as her sister, Florence. During her youth, she enjoyed ballroom dancing with her brother George. Despite being engaged twice, Rosina chose not to pursue a career or married life. Instead, she devoted her time to caring for her brother Stanley, who sustained severe injuries in Dunkirk during World War II.

At some point, she lost contact with her brother David, but she remained closely connected with her sister Florence and her extensive family. In the 1960s, she moved in with her brother Stanley to Sunbury-on-Thames, and she resided there until she moved into a nursing home in West Byfleet in 2015. Her older brother, Stanley, who suffered from significant facial and stomach injuries, passed away in 2005 at the age of 93.