[1] Noelene's mother was Afghan-Aboriginal of Barkandji heritage, and her father was a white Australian, the head doctor of the New Broken Hill Mines.
[1][2][3] Trevor was a radiographer based in Darwin working on a program to provide X-ray screenings for tuberculosis in remote Aboriginal communities when Jeremy was born,[4] three and a half years after his sister art photographer and curator Nici Cumpston.
[4] When Jeremy was eight they briefly returned to Australia but then went back to Canada, and this time his father worked at the hospital base for the world's second largest nickel mine, in Thompson, Manitoba, located north of the 63rd parallel.
[4][5] He worked as general practitioner for some time before heading off to Perth for three years' full-time acting study at the Western Australian Academy of Performing Arts (WAAPA).
[4] Whilst in his final year at WAAPA in 1995, Cumpston worked as a GP full-time for six weeks during his holidays to save money, which enabled him to produce and then perform in the one-man play Shadow Boxing.
[12] In 2020 his license to practice expired and he was called on by AHPRA to provide proof of proper professional indemnity insurance coverage to the Medical Board of Australia.
[13] During his time in All Saints, Cumpston worked with his then partner, props buyer and later producer, Rachel Lane, who is the mother of his eldest son Hal, born in 1999.