 Before leaving Frankfurt , Grainger had fallen in love with Kwast 's daughter Mimi ; in an autobiographical essay dated 1947 he admits to being " already sex @-@ crazy " at this time . John Bird , Grainger 's biographer , also records that during his Frankfurt years Grainger began to develop sexual appetites that were " distinctly abnormal " ; by the age of 16 he had started to experiment in flagellation and other sado @-@ masochistic practices , which he continued to pursue through most of his adult life . Bird surmises that Grainger 's fascination with themes of punishment and pain derived from the harsh discipline to which Rose had subjected him as a child . 
