Kay will never know whether reporting her 14-year-old son Jon to social services for sexually abusing a neighbour's child prevented him from moving on to become an adult paedophile in the style of Ian Huntley and Roy Whiting. Would he have been another Chris Langham, who was last week found guilty of downloading sadistic and depraved child pornography? Or a Timothy Cox, recently put inside on an indeterminate sentence for running an internet chat room where punters watched filmed abuse of children, including the rape of babies?
It is certainly possible, says Donald Findlater, deputy director of the Lucy Faithfull Foundation, where he works therapeutically with paedophiles. He hears time and again how their abusing began when they were children: "A 35-year-old man who came to me had started as a nine-year-old. By the time I saw him he had abused more than 500 children."
Such revelations rarely make us question what leads a nine-year-old boy to do this, but increase the cry for ever more punitive measures to deal with adult offenders. Earlier this year the government raised the possibility of chemical castration. While Kate McCann and her husband must face the fact that child abduction and trafficking is one way that children end up appearing in the kind of pornography watched by Langham.
But we ignore the fact that the child may be the father of the adult paedophile. Twenty per cent of people convicted of sexual offences are under the age of 20, according to the Home Office. Victim surveys report that 30-50 per cent of child sex abuse is carried out by young children and adolescents. Some 50 per cent of adult sexual offenders report sexual deviance in adolescence.
Paedophiles do not just appear fully formed as adults, says Andrew Durham, who works with child sex abusers for Warwickshire Council. "But fear and loathing of paedophiles blocks people from understanding the importance of their child hood circumstances. There is always something in childhood that breaks down the moral compass, in my experience. Many feel inadequate and isolated misfits who cannot form relationships with their peers. They gain power and control through abuse of younger children."
Preventing more victims lies at the heart of the work of Eileen Vizard, consultant child and adolescent psychiatrist and clinical director of the NSPCC's National Child Assessment and Treatment Service. For more than 20 years she has researched, diagnosed and treated some of the country's most disturbed and dangerous children who are sexually abusing others and who, if not helped to stop, may be on a trajectory that will lead to compulsive abusing as an adult.
Vizard led and co-authored the recently published first major study into this phenomenon, entitled Links Between Juvenile Sexually Abusive Behaviour and Emerging Severe Personality Disorder Traits in Childhood. It was funded by the Home Office and published on their website in November last year.
This is a three-year study of 280 identified juvenile sexual abusers, more than 90 per cent male. Abusing had very occasionally begun as young as at five-and-a-half years, although 14 years was average. More than half had abused victims five years younger than themselves and the majority abused female victims. There are great similarities in the behaviour of young abusers and adult offenders. Most had abused relatives, friends and acquaintances. In more than half the cases there had been penetration, masturbation and oral sex; one-third used verbal coercion. In some cases there had been co-abusers.
The extent and reality of child-on-child sex abuse is shocking, but so are the childhood experiences and circumstances child abusers endure. Without exception, they share childhoods that should not be tolerated in a caring society.
A quarter endured physical abuse, 74 per cent emotional abuse, 71 per cent sexual abuse; 92 per cent were exposed to domestic violence and 73 per cent experienced family breakdown. Nearly half were found to have "inadequate sexual boundaries". The research divided juvenile sexual abusers into "early onset" - those beginning before the age of 11 - and "late onset" beginning after this age. The first group were more likely to have experienced inadequate family sexual boundaries; multiple forms of abuse, poor parenting and insecure attachment. The latter group misused substances, targeted specific groups and often used verbal coercion.
Vizard sees a "developmental trajectory" where the abusers may be having sexual fantasies and beginning harmful behaviour towards other children. She says: "Without help, some sexualised children may move on to abusing other children at home or at school, later masturbating to sexual images of children and becoming entrenched in patterns of frank sexual abuse of children."
The research also shows a sub-group with emerging severe personality disorder who are more likely to have an early difficult temperament; more insecure attachment; inconsistent parenting; placement disruption and parents with mental health problems. Their sexual abusing is often premeditated and predatory. The fear that child abusing may increase through the stimulus of online child pornography which more and more children and young people access is chillingly real. The web features in half the cases of child-on-child sex abuse cases that Andrew Durham sees each year. "When young people see adults abusing children on the net, it normalises what is being done," he says.
The Taith Project, managed by Barnardo's, gets referrals of eight- to 18-year-olds from across Wales with "concerning" sexual behaviour. De nise Moultrie, the children services manager, says: "Particularly worrying about chat rooms is not just the images of child pornography being seen but the relationships children get into online around what they see."
The importance of taking the acts of young abusers seriously cannot be overstressed, says Vizard, who believes that as a society we have to do better than merely condemn paedophiles as depraved monsters as though they existed outside normal humanity; we have to understand how damaging their childhoods can be.
This is not indulgent liberalism, but a conviction, built on many years of learning how young abusers think, feel and behave, that potential victims could be protected by the kind of work that she and others are doing. What is needed is sufficient public support to ensure that the funding is made available to do this work on the scale that is needed.
Moultrie stresses that we are talking about children right across the social scale: "I think we are hugely handicapped in getting support because of public revulsion. A lot of professionals don't want to acknowledge that children are sexual abusers of other children. Parents read newspapers and don't want to identify their child as a monster, so they may reject the child or deny what is happening." Others, who might be prepared to support funding for children who are being abused, do not recognise that young people who are abusing other children may also need support.
Yet Vizard has seen how, with intense therapy, young abusers change direction. Their disturbing and distorting experiences are addressed; they are helped to see why the way they are acting is wrong and the impact they have on victims. They are taught techniques based on cognitive behavioural therapy for dealing with feelings and impulses in a non-damaging way, rather than leaving them to develop the compulsive behaviour that makes adult paedophiles so very dangerous.
Durham is confident that working with young abusers makes a difference: "You can get remorse at what the victim has suffered. These young may not have reached the stage of blocking out empathy and they are capable of forming a relationship with me as a safe adult. So they will listen and see that they can choose to learn not to follow the path they have taken. We have been going 12 years and have a very low rate of repeat sexual offences."
Kay is one of an increasing number of mothers of teenagers who tell the Stop It Now! helpline - set up for those who are abusing or fear they may - about their problem. She says that reporting Jon was agonisingly difficult, but through his treatment, in which she was involved, he learn ed techniques for controlling his behaviour.
"We have learned to communicate as a family and to talk about whether a situation is 'safe' for him. He has a therapist and I feel so very grateful that through this work Jon has taken responsibility for changing."
But if that constructive help had not been available, she dreads to think what might have happened.
Stop it Now! helpline 0808 1000 900