Simon Cole can pinpoint the moment his life took a wrong turn. It was the 1970s, and Scout leader Rod Corrie, who would later be convicted on repeated child sex abuse charges, put his hands down Simon's trousers. Simon was 10. Fear lodged in his psyche, where it has remained ever since. The act, the first of many, took only minutes, but the repercussions have lasted a lifetime.
Cole, growing up in Sydney's north, was academically bright and a keen sportsman. Now middle-aged, externally he has created a successful life - as a senior government policy adviser - but he is battling anxiety, depression and occasional suicidal thoughts.
Despite the fact he is a good-looking man who has attracted his fair share of female interest over the years, he remains single; intimacy is something he has never managed to work out.
As Rolf Harris this week appeared in a British court to plead not guilty to charges of having indecently assaulted young girls in the 1980s, it's easy to forget how attitudes towards paedophilia have changed. Looking back, Cole was not only the victim of a paedophile but of a culture that was ambivalent in its attitude towards sex and children.
In 1976, Britain's National Council for Civil Liberties - now known as Liberty - made a submission to parliament's criminal law revision committee, stating: ''Childhood sexual experiences, willingly engaged in with an adult, result in no identifiable damage.''
What was really needed, it argued, was a change in the attitude that assumed that all cases of paedophilia resulted in lasting damage.
Nowhere was society's equivocal stance more evident than in the entertainment industry.
When an American band, Gary Puckett and the Union Gap, made No.1 in the British charts with their single Young Girl - introduced on Top of the Pops in 1968 by Jimmy Savile - no one raised an eyebrow at the lyrics, in which a man bemoans the discovery that his girlfriend is below the age of consent. (And in the classic tactic of blaming the victim, it makes reference to ''that come-on look'' in the girl's eye). Twist the kaleidoscope to the current climate, and what was once an anodyne pop song now reads like a hymn to paedophilia. So much has changed. In the wake of the Savile investigation in Britain, which has embroiled dozens of celebrities, it is hard to believe that such an argument as suggested by Liberty could ever have been deemed worthy of public scrutiny. Yet it has, on occasion, reared up several times over the decades in research papers in Europe and the US.
Earlier this year, The Guardian ran an article about paedophilia that stated: ''There is, astonishingly, not even a full academic consensus on whether consensual paedophilic relations necessarily cause harm.''
Astonishing indeed. But is it really the case? ''To say there is no consensus on the harmfulness of child abuse is much like saying there is no consensus on climate science - which is to say there is a strong consensus, but there is a vocal group of people largely on the margins of the debate who like to make claims to the contrary,'' says Michael Salter, lecturer in criminology at the University of Western Sydney.
What muddies the waters is that research challenging the harmfulness of child abuse can be put forward by parties who may have an ideological axe to grind.
In 1998, a meta-analysis study by Rind et al published in the US's Psychological Bulletin found that the level of harm caused to children is greatly exaggerated. The paper created controversy when its contents were first aired in public, and its conclusions were unanimously denounced by the US House of Representatives - the first time in American history that a scientific study was formally repudiated by a legislative body. Two of the authors had been keynote speakers at conferences of notorious pro-paedophile advocacy groups, and had also written for Paidika, the pro-paedophile's magazine of choice.
More to the point, can paedophilic relations ever be ''consensual''? ''The idea that a teenager is on an equal playing field with an adult male and can consent on that basis is farcical,'' says Salter, who has spent the past six years researching sexual offences against children. ''It is what we call cognitive distortion, in that they are working pretty hard to legitimise their behaviour.''
What the research does show is that the harm caused by sex abuse varies, depending on the child's age, gender, and family set-up. Salter is wary about making generalisations, but it stands to reason that the younger the child, the more he or she is to be harmed. As children get older, the picture blurs.
Latest figures suggest that up to one in five women experiences sexual abuse in childhood, and about one in 10 men.
Sexually abused girls fare worse than boys because they are more likely to go on to experience further abuse later in life. ''The public health evidence clearly shows that the health outcomes of sexually abused girls are quite poor,'' Salter says. ''We have gold-standard evidence that the burden of mental illness borne by women is closely linked to the harms of child sexual abuse.''
Why do men harm children? Often they want to feel powerful and in control. In a society that craves physical perfection, children embody all the attributes we have come to value, in that they are slim, hairless and still in the possession of taut, unblemished skin. The term paedophile, sex offender and child molester are interchangeable, it seems, depending on whether you approach it from a psychological, legal or social standpoint.
A paedophile is, according to the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, someone who has a primary or exclusive sexual interest in pubescent or prepubescent children. But not all paedophiles are child molesters; that is, they do not always act on their impulses. Debate also rages about what causes it - whether it is innate or acquired.
MRI scans reveal a possible issue with paedophiles' ''white matter'' - the signals connecting different areas of the brain. In February 2011, psychologist Vernon Quinsey, a professor emeritus at Queen's University, Canada, told parliament that paedophilia should be classified as a sexual orientation. ''As far as we know - and many people have tried - these sexual interests are not modifiable by any method that's been tried yet.'' But others are sceptical about pigeonholing it in this way, and are ambivalent about summing up a complex issue in just one word.
Stephen Smallbone, a psychologist and professor of criminology at Griffith University, Queensland, says: ''I tend not to use the word paedophile that much … it conjures up stereotypes which are incorrect.''
By this he means the image of the monster, the dirty old man in a flasher coat, the creep with lollies who preys on kids and is the stuff of parental nightmares.
From his experience, men who harm kids tend to be much less obvious - white, mid-30s, married with children. Why do they do it? Often, because they can.
Smallbone believes that the problem should best be defined through law. In his view, people who sexually abuse children are merely criminals, and should be treated as such. There is no special psychiatric category to define the work of thieves and murderers, nor should there be for anyone who commits a sex act on someone under the age of 16.
From an evolutionary perspective, humans have a biological drive to find young, suitable partners. That still exists. What has changed are the social rules. In the same way we no longer send children down mines and pocket their pay, we have finally become sensitive to their sexual exploitation. Not so long ago, the signal for sexual availability was the onset, not the end, of puberty. In the US state of Delaware in 1895, the age of consent was seven. ''What we are dealing with now are very sensible laws, and people ought to know that if you have sex with someone under the age of 16 then you are breaking the law.''
While the vast majority of sexual abuse takes place with pubescent children, what about the small number of males who commit acts of indecency on the very young? Smallbone and Salter say these men - and they are nearly always men - exist on the margins.
But they are the ones who attract the media glare, drawing attention away from the main perpetrators - the fathers, uncles, stepfathers and neighbours. This preoccupation with a small sub-group detracts from the bigger picture, researchers say.
''I don't think there is any other area in science where people think it is acceptable to generalise from the most extreme cases,'' Smallbone says.
Salter says: ''We know that a significant proportion of men that offend against children have also offended against adults. This desire to categorise offenders into distinct boxes just is not justified by the evidence.'' Others remain unequivocal. A Harvard health publication from 2010 states bluntly: ''Paedophilia is a sexual orientation and unlikely to change.''
So what do we know about sex offenders? For a start, they tend to be criminally versatile. Often, they already have broken the law and have experience in exploiting others.
The average age they start offending is 32, and more than half of them live with their victim. They are capable of empathy, but may go to great lengths to construct explanations in their own heads that justify their abuse. In other words, framing the world in their own narrative. And they feel isolated. If society turns them into monsters, then who are they able to tell?
Adults Surviving Child Abuse: see asca.org.au; 1300 657 380.