Heretic TOC yesterday promised a return to more challenging material in this post. This follows a reader’s request to provide details of my further exchanges with Dr James Cantor on white matter in the brains of paedophiles. So this post will be somewhat technical, and lengthier than usual.

Just to recap and set the scene, what follows is a short extract from near the start of my email on the subject to the totally brilliant and utterly wonderful blogger Neuroskeptic. No, honestly, it is a very impressive blog, but I feel obliged to lay it on a bit thick as Heretic TOC  been honoured by a visit and comment today from him (could be a “her”, I suppose, but no indication to that effect). So, the extract:

An interesting study in this area was J.M. Cantor et al.’s sMRI paper “Cerebral white matter deficiencies in pedophilic men”. Journal of Psychiatric Research, Volume 42, Issue 3, Pages 167-183 (2008).

The study looked for brain regions that distinguish pedophilic from nonpedophilic men. Pedophiles were found to have less white matter. The authors suggested that the regions in question operate as a network for recognizing sexually relevant stimuli and that pedophilia results from a partial disconnection within that network.

The work is one of a series of papers purporting to indicate that pedophiles have brain deficiencies resulting from “perturbation” of prenatal development, and other misfortunes such as trauma from childhood head injuries. Papers have shown lower average IQ of pedophiles and far more left-handedness than average.

Those who really want to know about all this stuff need to read Cantor’s paper and some of the theory behind my proposed alternative, which is grounded in current understandings of brain plasticity. The key scientific development is the field of epigenetics, which is all about how environmental effects can feed back into our fundamental biology, including brain structure. The mechanism for this is gene expression i.e. the environment can alter which of our genes are switched on and switched off, with massive effects.

For quick background, if you feel you need it, see two of my Heretic TOC postings Scientific egos as fragile as eggs and The dubious analogy of the ‘extra arm’. These posts describe my initial engagement in debate with Dr Cantor on the Sexnet email list-serve forum. What follows is a further Sexnet post, by me. This Sexnet posting follows a couple of sharp exchanges on Sexnet between Cantor and myself, in which he had accused me of being “an impostor” (sic). It was following this element of personal abuse by Cantor that the moderator, Dr Mike Bailey, stepped in to say “let’s take the insults offline” (see below). My reply follows on from this. In it, as you will see, I refer to a second, more recent, paper by Cantor (co-authored with Blanchard).


Mon, 31 Dec 2012 at 18:46

>let’s take the insults offline.

Damn! Yesterday, just when I had a real zinger on the way, the ref steps in! 🙂

OK, I’ll back off from anything that might be considered provocative, but I hope I may be allowed to address the “impostor” point, not in order to hurl any insults but to defend myself against one. I fear the humour with which I had intended to respond will be seen as just such a provocation, so I’ll keep it straight: I asked the question at issue as a layman seeking information, and did not present myself as anything else. I have now been challenged to “produce an alternative explanation for the handedness findings” as though I were an expert. This flatters me. I have never pretended to be anything of the sort. [Heretic TOC adds: finding of “far more left-handedness than average”: see above.]

The challenge does however suggest a further question: Does the epigenetic explanation I proposed (again, simply as a curious layman) as an alternative to James’s account of paedophilic white matter structure stand or fall on the basis of handedness findings? If so, why?

The only clue I can find on this in James’s Sexnet posts is in the reference he made to his encounter with Susie Orbach on BBC radio. James wrote:

Had she asked me whether being abused could cause the differences in the brain, I would have let her know that abuse is indeed reflected in brain anatomy, but not in any of the areas I found to be related to pedophilia.  (And I would have reminded her about implications of the handedness findings, which kept slipping her mind.)

The fact that the claimed implications of the handedness findings “kept slipping her mind” suggests either Orbach just wasn’t “getting it” or else she had some positive reason for rejecting the claims. I guess we’ll never know her reasoning; I could ask her but I am more interested in James’s, and the brevity of his remarks above doesn’t give much to go on. I will stick my neck out to interpret him, though, to agree that, yes, it is known that “abuse” which produces high levels of stress, such as children being persistently shouted at, or under frequent threat of violence, or subjected coercively to sexual impositions, can result in anatomical brain changes and that, yes, those changes have not been found in the areas where James has found differences in paedophilic white matter.

But no one is proposing (or not me anyway) childhood stress-induced brain changes as an alternative to James’s explanation of paedophilic white matter differences. I (provisionally) see paedophilia and hebephilia as non-pathological variations of sexual orientation, ranging from exclusive paedophilia (<5% of the adult male population) to a substantial, but non-preferential, attraction (up to 25% of the adult male population) at least if paedophilia and hebephilia are considered together. I wonder if James would predict that up to 25% of men – up to a quarter in various studies have been shown to have some sexual attraction to prepubescent or early pubescent children (i.e. children of pre-adult body morphology), or have admitted it – have some degree of white matter deficiency compared to the remaining 75%? Would it in principle be possible to plot a man’s (or an averaged large cohort of men’s) degree of white matter deficiency alongside the degree (as measured by penile plethysmography, say) of his attraction to children? Would James expect to find a graded matching of those data for a quarter of the male population? It seems somewhat implausible. If, alternatively, he is limiting his theory to a definitely small (<5%, perhaps 2-4%) group of paedophiles with pre-natal and infantile developmental problems, how then does he account for a substantial level of paedophilic attraction in around a fifth (25% – 5% = 20%) of male adults? For this he presumably has to invoke (not very parsimoniously) a second theory.

In Cantor & Blanchard 2012 no distinction is found between white matter structure in hebephiles as compared with paedophiles. This provides another problem for the developmental theory, as it would predict hebephilia as an intermediate type between paedophilia and teleiophilia. The authors respond by saying:

On the other hand, children in Tanner Stages 2 and 3 — the preferred sexual objects of hebephiles — might be perceived as physically more similar to children in the later years of Tanner Stage 1 than to fully mature individuals (Tanner Stage 5) by the average human observer. If that is true, then one might expect hebephiles to be more similar to pedophiles than to teleiophiles on relevant neuroanatomic parameters.

Well, the average Martian observer might be in no doubt, but my guess is that “the average human observer” would be very hard pressed to say that a youngster at Tanner stage 3 was more like a child than an adult, or the other way round. So would Tanner himself, I imagine, which would hardly be surprising as this morphology is bang in the middle of his 1-5 scale. The Cantor/Blanchard argument might work for Tanner stage 2, but this line of reasoning still looks very unconvincing.

One point to bear in mind here is that objective categorization misses the arguably more relevant subjective psychology of the hebephiles themselves. I know of many hebephilic men, often those who are married and have a substantial level of attraction to women, who report pubescent boys as highly attractive, and yet they are not at all drawn to prepubescent or adult males. This cuts right across Ray Blanchard’s alloerotic findings, which is a shame because I love his beautiful graphs and elegant exposition. Also, those who would otherwise lean towards paedophilia and teleiophilia can each be hebephilic in different ways. As Confucius said about homosexual hebephilia (but don’t ask me for the exact reference!), “The boy-lover sees the boy in the youth; the gay guy sees the man”. “Boyish” and “manly” aspects can be perceived in one and the same youth: beauty (and sexual attractiveness), and what characterises them, are indeed in the eye of the beholder.

Epigenetic factors, by contrast to James’s theory (or theories), impact upon everyone in ways capable of giving expression (gene expression, actually, or suppression) to an infinite range of personal experience. And the beauty of Jim Kohl’s pheromone idea, is that it offers a precise biological explanation of how sexual learning, including sexual orientation and even preferences such as a shoe fetish, is fed back into a person’s gene regulation following initial conditioning of a preference to a pheromonal stimulus in the learning environment. In the case of paedophilia, this would mean sexual arousal to child-related sensual stimuli (visual, auditory, tactile, etc.) once these had been conditioned from an association with the pheromone, this being theoretically the primary (olfactory) stimulus.

Jim sees a role particularly for luteinizing hormone (LH), noting that LH is an important indicator of steroid hormone-mediated mammalian brain development. Significantly, in relation to James’s work, this brain development includes LH-driven changes in the ratio between white and gray matter.

This is admittedly all very speculative and Jim has long been treated somewhat dismissively here, but I see that he is no longer such a lone voice. Epigenetics, and quite possibly a role for human pheromones as an agent of epigenetic change, are beginning to look serious players in human sexuality.

Returning to handedness, I have no problem in seeing that it is not relevant to childhood brain changes beyond infancy (such as those caused by stressful abuse) but is relevant to pre-natal and infantile developmental “perturbations” that might also cause white matter differences.

As it happens, I have never contested any findings on handedness, digit ratios, etc., as markers of pre-natal or infantile developmental “perturbations”, whether in gay men or paedophiles. On the contrary, these effects seem highly plausible even though the research is dogged by contradictory results and low effect sizes, as is often the case in science: the “fog of war” is not untypically dense and slow to clear. However, until I hear otherwise, I do not see why acceptance of such findings commits anyone to the proposed explanation of observed white matter structural differences. Various bits of evidence may look as though they fit together like pieces in a jig saw puzzle, but there is sometimes a temptation to force a fit: the pattern suggests it must be the right piece, but the shape just isn’t quite right. Apologies if this is a misleading metaphor! And apologies for going on a bit.

Tom O’Carroll

Cantor JM & Blanchard R, White Matter Volumes in Pedophiles, Hebephiles, and Teleiophiles, Arch Sex Behav (2012) 41:749–752


My question this time to James Cantor was “Does the epigenetic explanation I proposed…as an alternative to James’s account of paedophilic white matter structure stand or fall on the basis of handedness findings?”

That was a month ago. He has not responded.