He also said he is haunted by a sense of rejection because his single-parent mother gave him up for adoption as a baby.
In Beware of the Dog, he claims the two childhood traumas were responsible for his competitiveness on the field.
He also blames them for his two failed marriages, saying they have blighted his life.
The former Harlequins and England hooker, 47, who was capped 64 times, describes how, when he was nine or ten, he and three other boys were drawn by their teacher into sexually abusive games in a tent during an overnight field trip in Yorkshire.
The teacher, now dead, is not named, but he was a churchgoing friend of Moore's adoptive parents, both Methodist lay preachers.
The teacher continued to abuse the boys in a classroom storeroom. Moore was too ashamed to tell his parents.
Moore, now the father of two small girls and married to third wife Belinda, was known as Pitbull during his long rugby career.