Biological influences in pedophilia
The first of these is the mean IQ of various groups. IQ, in this context, might be thought of like blood pressure—a general indicator of overall health of the brain (instead of the heart). Although they were not planning to conduct research with these data, we actually do have reports on the IQs of thousands of sex offenders. Starting in the 1930s, measuring IQ was often a part of a comprehensive health assessment, and such assessments were routinely conducted by various institutions, including prisons. In order to find out whether there was any pattern, my team pulled together all available reports, pooling the samples into men who committed sexual offenses againstOver most of the 20th century, “nurture” theories of pedophilia were much more popular than were “nature” theories. Over the past decade, however, findings been reported that can be explained only by the presence of biological factors.
The first of these is the mean IQ of various groups. IQ, in this context, might be thought of like blood pressure—a general indicator of overall health of the brain (instead of the heart). Although they were not planning to conduct research with these data, we actually do have reports on the IQs of thousands of sex offenders. Starting in the 1930s, measuring IQ was often a part of a comprehensive health assessment, and such assessments were routinely conducted by various institutions, including prisons. In order to find out whether there was any pattern, my team pulled together all available reports, pooling the samples into men who committed sexual offenses against
Another pattern also emerged from this analysis. Although very many studies categorized people into “offenders against children,” they did not all use the same definition of “child.” That is, some studies had “offenders against children under 18,” and others had “offenders against children under 16,” etc. This showed a systematic pattern: The more stringent the definition of child, the lower the mean IQ of the sample. That is, the more pedophilic the sample likely is, the lower its mean IQ.
Using the data archived in our own clinic, we found the same pattern for verbal memory tests, visuospatial memory tests, histories of failing grades in school (or being assigned to special education classes), having been knocked unconscious (before age 13), being physically shorter in height (by 2.5cm—roughly double the effect of smoking during pregnancy), and triple normal rates of non-right-handedness (the same range as observed in schizophrenia). Because characteristics such as handedness exist prenatally (fetuses show a hand preference in thumb-sucking), whatever chain of events leads to the development of pedophilia, it had to have been present prenatally.
Using the data archived in our own clinic, we found the same pattern for verbal memory tests, visuospatial memory tests, histories of failing grades in school (or being assigned to special education classes), having been knocked unconscious (before age 13), being physically shorter in height (by 2.5cm—roughly double the effect of smoking during pregnancy), and triple normal rates of non-right-handedness (the same range as observed in schizophrenia). Because characteristics such as handedness exist prenatally (fetuses show a hand preference in thumb-sucking), whatever chain of events leads to the development of pedophilia, it had to have been present prenatally.
Imaging pedophilic brain structure
Early studies of the brain in pedophilia were conducted largely with CT scans and provided inconsistent results. The advent of MRI-based scanning dramatically increased the clarity of images, permitting more precise measurements. Our first MRI study used conventional (T1-weighted) scans of the brain and indicated that pedophilic men differ from men who committed non-sexual crimes in having less volume in large white matter regions. White matter is the brain tissue that connects brain regions, permitting those regions to function as a single network.
We are currently gathering data, using more newly developed neuroimaging techniques to pursue this farther. I am grateful to the Canadian Institutes for Health Research for enabling this work.
We are currently gathering data, using more newly developed neuroimaging techniques to pursue this farther. I am grateful to the Canadian Institutes for Health Research for enabling this work.
Minor Physical Anomalies (MPA's)
One of the most important issues for understanding the development of pedophilia is to learn when the chain of events that causes it began. Certain features of the human body develop at specific points in life. Thus, detecting differences in these features can reveal clues as to when in development pedophilic individuals began to differ from non-pedophilic individuals. To search for evidence of perturbations of physical development, we have begun a project to record the occurrence of physical characteristics that form early in life and sometimes before birth. This project has thus far demonstrated that pedophilic men are physically shorter than non-pedophilic men. We are currently gathering data on minor physical anomalies (MPAs), medically inert physical characteristics of the body that form before birth. I am grateful to acknowledge support for this project from the Canadian Institutes for Health Research.