For the study, a team of North American researchers compared two samples of individuals with and without an intellectual disability and a history of sexual offence. The team found that sexual offenders with intellectual disability who had committed a serious sexual offence, such as rape or paedophilia, actually exhibited a greater sexual knowledge than non-offenders.
According to the authors, this improved sexual knowledge may be coming from "corrective" sex education that the offender was given in the past. After thorough analysis, researchers concluded that the higher level of knowledge of those who had committed some form of sexual offence was the direct result of their exposure to formal or informal sex education.
They said that the data indicated two categories of persons with intellectual disabilities that sexually offend: Individuals who are knowledgeable and who offend in more serious ways and Individuals who appear to have a lack of sexual knowledge and whose offence may be the result of that lack of knowledge. The latter is termed counterfeit deviance.
"We simply cannot treat all sex offenders as 'counterfeit deviant' and excuse their behaviour as a result of inadequate knowledge. We need to establish whether sex education is needed as an element of a comprehensive treatment package," said Shelley Watson, a graduate student from the University of Alberta.
People with intellectual disability were also found to be typically very conservative when it came to sexual attitudes. However, the researchers found that serious sex offenders actually expressed much more liberal attitudes when it came to sex, including same-sex relationships, than sex offenders who only committed sexual inappropriate behaviours, such as public masturbation or inappropriate touching.
"This study provides support for the need to assess sexual knowledge, sexual attitudes and prior sex education when an individual commits a sexual offence," Watson said. "Only a careful diagnosis will reveal whether the offence is motivated by sexual urges and fantasies consistent with serious sexual offence or by other factors," she added.
The study is published in the Journal of Intellectual & Developmental Disability.