An haifi Sia Kate Isobelle Furler a ranar 18 ga Disamba, 1975 a Adelaide, Kudancin Ostiraliya. Mahaifinta, Phil Colson, mawaki ne, kuma mahaifiyarta, Loene Furler, mai koyar da zane-zane ne. Sia ita ce 'yar'uwar actor-singer Kevin Colson. Sia ta ce tun tana yarinya ta kwaikwayi salon wasan kwaikwayon Aretha Franklin, Stevie Wonder da Sting, wanda ta ambata a matsayin tasirin farko. Ta halarci makarantar sakandare ta Adelaide. A tsakiyar shekarun 1990, Sia ta fara aiki a matsayin mawaƙa a cikin ƙungiyar jazz na gida Crisp. Sia ta yi aiki tare da ƙungiyar kuma ta ba da gudummawar murya ga kundin waƙar su Word and the Deal (1995) da Sia EP Delirium (1997). Tambaya: Wanene kawun?
Kevin Colson