Editor's Note: Dr. James Cantor is a professor at the University of Toronto Faculty of Medicine and has been conducting research on the causes of pedophilia for the past 10 years. He is the Head of the Law & Mental Health Research Section of the Centre for Addiction and Mental Health (CAMH; Toronto) and the Editor-in-Chief of Sexual Abuse: A Journal of Research and Treatment.
(CNN) -- The on-going reports about child molestation in the Catholic church have led the public and the media to ask what causes someone to be sexually attracted to children. Scientists use the word pedophilia to refer to the sexual preference for children before puberty (usually, before age 11), and the word hebephilia, to refer to the sexual preference for children at puberty (usually, ages 11 to 14).
Although there have been claims that child molestation is a result of homosexuality (or of celibacy), there is absolutely no basis in science for either conclusion. The scientific evidence instead suggests that pedophilia and hebephilia are caused by atypical brain development occurring near or before birth.
MRI research has found very large differences in brain structure between men who have a sexual preference for children and those who have a sexual preference for adults. These differences were detected as regions of low density in brain tissue called white matter. White matter is what connects the various parts of the brain, enabling it to function as a whole. The white matter that is affected in pedophilia and hebephilia is the white matter that connects the parts of the brain that respond to sexual images. (Specifically, these regions were the superior occipitofrontal fasciculus and the arcuate fasciculus.)
There does not exist any evidence that gay men share this feature of decreased white matter. In fact, there is some evidence that gay men have areas of more white matter than straight men, in at least some parts of the brain (called the corpus callosum).
Also demonstrating that gay men have no more of a sexual interest in children than do straight men are studies that have measured sexual responses directly: There exists a test, called a phallometric test, in which a man is shown images of adults and children, both male and female, while he wears a device on his penis to detect even very small changes in blood volume. The procedure is routinely used with sexual offenders, and research has repeatedly shown phallometric testing to be one of the most -- if not the single most -- accurate predictor of who is the most likely to commit future sexual offenses. When regular gay men and regular straight men (not offenders) are tested, gay men respond to images of children in exactly the same way that straight men do: very little.
Out of typical men, approximately two to three percent have a sexual preference for men rather than women, and out of pedophilic/hebephilic men, approximately 20 to 30 percent have a sexual preference for boys rather than girls. It is an error, however, to conclude from this that the two to three percent who prefer men are more likely than the others to break out of their preferences to contact a child sexually. That is, the offenses against boys are being committed by the 20 to 30 percent of pedophiles who prefer boys, not by the two to three percent of otherwise typical men who prefer men.
The misconception that gay men pose a disproportionate risk to children comes from a misunderstanding of men's sexual preferences: Pedophilia is the genuine sexual preference for children. The evidence suggests that these are innate and immutable characteristics. Pedophilia/hebephilia is not a temporary state from which those who prefer boys can become typical gay men, nor from which those who prefer girls can become typical straight men. Nor is there any known route by which someone with a genuine sexual preference for adults can develop a genuine sexual preference for children, either girls or boys.
Although it is reasonable to question why the Catholic priesthood appears to include so many pedophilic or hebephilic men, there is no scientific evidence that homosexuality is the answer, nor that fostering discrimination against gay men could be a solution.
The opinions expressed in this commentary are solely those of Dr. James Cantor. Click here more information and updates on his research.