Jack Body was born 7 October 1944 in Te Aroha, a town in the North Island farming district of the Waikato. Both parents came from farming families; his father, Stan, was an earthmoving contractor. Seeing his older sisters take piano lessons, Body convinced his parents to let him follow suit, and began piano lessons from William Cranna, a graduate of the Royal Scottish Academy of Music and employee of the local power board. Body's first composing efforts as a child were re-composing his prescribed Royal Schools exercises and performing them at end-of-year piano recitals in the local church hall.