We all like to categorize things. Categorization is an aid to thought and memory. It is doubtful we could think much at all if we couldn’t make generalizations to handle large amounts of data conveniently.
Organizing things by type is such a powerful tool that we overuse it. A long-standing division of sexual offenders is into two main groups: child molesters and rapers of adult women. A similar system of classification divides out a third group: perpetrators of incest. These categories are not without basis. There is a bimodal distribution of age at first arrest, with the adult rapists at 14-17 years, usually for nonsexual offenses, and the child molesters at 31-35, nearly always for sexual offenses. The adult rapists are more likely to have property, drug, and violence offenses in their criminal records; the molesters of children have stronger work records and more paraphilias. There is also considerable justification for separating out incest perpetrators, as a significant minority offend for “only” a limited period under great stress.
But these categories, while not useless, are quite porous. If you work with the sex-offending population, you keep coming up against exceptions. We have tended to explain these away with yet more categories in the past. “Oh, he’s Mild MR,” or “But he’s got some neurological involvement.”
Yet as the sexual history slowly unfolds, there is a great deal of unexpected crossover. The child molester’s sister reveals that he forcibly raped her when she was 17; the step-dad convicted of an incestuous relationship with his 14 year old daughter had a previous accusation, twenty years ago, of babysitter molestation of a five year old boy. Categories fall apart.
Knight, at Bridgewater State, divided offenders into six groups. A Canadian group suggests that these six should be subdivided into 20. I don’t hold with any of those systems; we now use spectrum measures of violence, paraphilias, usual victims, and social integration. Head injury and substance abuse, the major wild cards, also get close attention. We can afford to be this unstructured because we’re old, and can’t get the
three old categories out of our heads after so many years, providing a framework.
Treatment now centers on accurate assessment (which drives risk, placement, and supervision) and reducing risk factors. That’s a whole different discussion, which I leave off here. Key concepts: frontal lobes, executive functions. Anything which interferes with the frontal lobes, such as head injury or substance abuse, sends reoffense rates through the roof.