Dissociation is not a child's choice. The creation of an amnestic self is a survival mechanism of the brain. It allows a child to function in everyday life while at the same time being traumatized repeatedly. Although the child has no memory of the abuse, she may carry over into her "normal" life a strong sense of guilt, shame, secrecy, and fear which will impact her, at the very least, into her adult life.
Dissociation is often discussed as being on a continuum. All of us experience dissociation to some degree. Highway hypnosis is the most common. We drive. We zone out. We snap to and don't remember the last 10 minutes or the last few exits. Going through the spectrum is post-traumatic stress disorder (PTSD) which all victims of long-term childhood abuse are likely to develop. The extreme of the spectrum is Dissociative Identity Disorder (DID). It used to be called multiple personality disorder. Please don't let that stop you from reading further. This is where much of society has been misled and tends to be frightened.
Typically, if a child is going to develop DID, it has been decided subconsciously by age 6 and rarely after age 9. This is cited in the leading authoritative texts on dissociation by the country's experts on dissociation. Some of the books are listed as therapist resources on this blog.
For clarification, DID does not require sexual abuse specifically. It can be the coping mechanism for overwhelming physical, emotional, and/or sexual abuse. Given the inherent double bind of incest, children from incestuous families have a greater likelihood for abuse beginning at a very early age and continuing for a number of years. E. Sue Blume's "Secret Survivors" is an excellent book to learn the dynamics of incest to include victims who are dissociative.
