A girl and a man are sitting on a park bench. She's staring into a book; he's staring at her. After a while they start to talk and get into a friendly conversation. "Would you like to sit on my lap?" he asks softly. The stirrings of sexual excitement are faintly audible in his voice.

Uncomfortable, moviegoers squirm in their seats. They are watching Nicole Kassell's The Woodsman, a 2004 movie about the life of a pedophile. After 12 years behind bars for child molestation, Walter is trying to make a new life for himself. He has his own apartment, holds a job and has recently married. But the path to a normal existence is difficult. His co-workers are suspicious and give him the cold shoulder; his sister and the police have nothing but contempt for him. Viewers wonder whether such a man can ever find redemption. Perhaps he should be permanently removed from society.

The public does not like to take chances with pedophiles—people who are sexually excited by children. Some 89,000 children in the U.S. were sexually abused in 2002, according to the Department of Health and Human Services, and other studies suggest far higher numbers. Meanwhile one in seven youngsters aged 10 to 17 received an online sexual solicitation in 2005, reports the National Center for Missing and Exploited Children. Pedophiles are responsible for many of these solicitations and abuse cases. And among convicted pedophiles—especially those drawn to boys—the recidivism rate is high.

Yet not all adults who abuse children are pedophiles. Some of the abusers are not, in fact, especially attracted to children but target them because they are weaker and more pliable than adults. What is more, not all people who have pedophile tendencies act on them or turn violent. Indeed, given the consequences of being identified, many pedophiles remain undercover, surrounded by children while struggling with their secret desire.

And that can be dangerous.

Thus, some researchers are pushing the public to see pedophilia as a psychological disorder that calls for study and treatment--for no less a reason than the safety of children worldwide. The idea is to separate this mental state from criminal acts of child abuse, because the two do not always go hand in hand. This tactic, after all, may be the only way to attract into treatment the untold numbers of undiscovered pedophiles and reduce the chances that any of them will ever harm a child.

Officially Sick
In 1886 German psychiatrist Richard Freiherr von Krafft-Ebing coined the term "pedophile" (from the Greek pais, meaning "child," and philia, meaning "love" or "friendship"). Krafft-Ebing was also one of the first to separate the desire for children from the behavior of child abuse. In his then revolutionary work, Psychopathia Sexualis (Pyschopathy of Sex), Krafft-Ebing opined that sexually deviant thoughts were not criminal per se but should in some cases be seen as an illness. Indeed, pedophilia is present in the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). This volume defines pedophilia as all recurrent sexually exciting fantasies, impulsive desires and behaviors that include sexual acts with a child and that occur over a period of at least six months.

Krafft-Ebing also pioneered a distinction between hard-core pedophiles--those whose predilection came to the fore at puberty--and other forms of child abuse in which children are used as substitutes for adults. These pedophiles turn to children later, after an adult relationship has failed or they realize that the possibility of one is remote.

Among the latter class are "situational molesters." These people are usually incapable of having relationships with an equal--perhaps because of a mental disability--or may turn to children after experiencing frustration or humiliation in an adult relationship. In a subcategory called senescent pedophilia, for example, men target impressionable and compliant partners because of their own senility or increasing impotence. Situational molesters also include individuals who have ongoing contact with children because of their work, and thus may be drawn into situations in which they use their charges for their own sexual gratification.

Love Gone Awry
Research into the causes and treatment of pedophilia remains somewhat fragmentary. One deterrent to such research is that scientists and clinicians who study and try to treat the condition are often branded as supporters of illegal sexual acts against children rather than as people trying to understand and alleviate a psychiatric disorder.

Nevertheless, like other complex psychological traits, pedophilia is thought to stem from a combination of genetic and environmental factors. Many experts believe that disorders of sexual preference emerge from childhood experiences during critical periods in human development. In particular, several studies have confirmed that pedophiles are unusually likely to have been victims of violence and sex abuse as children. In one such study in 2001, researchers at the Royal Free Hospital School of Medicine and University College London reviewed the case notes of 225 male sex abusers and 522 other male patients being treated in a London clinic for sex offenders and sexual deviants. They found that abusers had themselves been victims of sexual violence considerably more often than the patients who had not committed sex abuse, suggesting a victim-to-perpetrator cycle in some men who commit sex crimes.

David Skuse and his colleagues at the Institute of Child Health in London went further, identifying other factors that push a male sex-abuse victim to commit a sex crime later on. Of 224 young male victims of sex abuse, 26 (12 percent) ended up committing sexual offenses, typically with children, by the time the researchers stopped following them seven to 19 years later. The victims who became perpetrators, the scientists reported in 2003, commonly had experienced neglect and lack of supervision, along with abuse by a female; often they had also witnessed violence among family members. Such a hostile childhood, psychoanalytic theory goes, can create a need to replace feelings of "defeat" with those of "triumph." To accomplish this emotional shift, a person may turn the tables and become the sexual aggressor as an adult.

In other cases, however, the abused or otherwise troubled pedophile seeks less to dominate than to establish a "genuine" relationship with a child, opines sociologist David Finkelhor of the University of New Hampshire. Such men tend to identify strongly with the thought patterns and lives of children, a trait that often goes along with a lack of education and of self-esteem. In such cases of so-called emotional congruence, a man may feel happiest and most secure when he spends much of his time with children and may even act childish himself.

Pedophiles often have other issues, too, according to Finkelhor, such as deep-seated sexual anxiety that blocks the development of normal sexuality. A general lack of inhibition rounds out the picture: pedophiles may suffer from psychosis, poor impulse control or alcoholism. Supporting the notion of pedophiles as impulsive, a research team led by psychologist Ronald Langevin of the University of Toronto discovered differences in an area of the frontal lobe in men who molest children as compared with normal men. This region of the brain is critical for impulse control among its other, higher-level reasoning functions.

Biology to Blame?
In some cases, the roots of pedophilia may be less psychological than biological. For instance, preliminary data from 2002 link childhood brain trauma to pedophilia. A research team led by Ray Blanchard of the University of Toronto took the medical histories of about 400 pedophiles and 800 nonpedophiles and found that the pedophiles were more likely than the others to have had accidents causing loss of consciousness before age six. (Such accidents were also associated with lower intelligence and educational level.)

That does not necessarily mean that the early brain trauma caused the pedophilia, the authors note. It is possible that pedophiles are more likely to have been born with brain defects that can lead to pedophilia and that also made them accident-prone (and thus more likely to fall and hurt their heads). In that instance, the brain injury would simply be incidental to the pedophilia and not a cause of it. Other brain-based abnormalities--such as attention deficit-hyperactivity disorder (ADHD)--have been loosely associated with both pedophilia and being accident-prone. (Although pedophiles are more likely than others to have been diagnosed with ADHD as children, this does not mean that children with ADHD are likely to become pedophiles.) [For more on ADHD, see "Informing the ADHD Debate," by Aribert Rothenberger and Tobias Banaschewski; Scientific American Mind, December 2004.]

Meanwhile, using family-history questionnaires, a team led by Fred Berlin at the Johns Hopkins School of Medicine found higher rates of pedophilia among members of pedophiles' immediate families than among the families of nonpedophiles. No one has found specific gene variants associated with pedophilia, however. Even if such genes are discovered, they are unlikely to fully account for the disorder.

Getting Help
Treatment for pedophilia typically involves a combination of talk therapy and medication. Psychotherapy can take one of two forms. Freudian psychoanalysis involves bringing to light traumatic events and identity crises from a patient's childhood so that such problems may be discussed and resolved. Cognitive-behavioral therapy, on the other hand, is geared more practically toward helping patients identify--and avoid--the kinds of situations that may tempt them to engage in harmful behaviors. Therapists may also try to correct a patient's cognitive distortions, such as the twisted notion that "the kid liked it."

Sex offenders who successfully complete a psychological treatment program are less likely to commit another offense, or if they do reoffend the crime is typically not sexual in nature, write University of Leicester criminologist Charlotte Bilby and psychologist Belinda Brooks-Gordon of the University of London in a July 2006 review in the British Medical Journal. But not all pedophiles respond to psychotherapy, Bilby and Brooks-Gordon observe.

For additional help in subverting pedophilia, doctors may also prescribe medications such as selective serotonin reuptake inhibitors (SSRIs). These drugs are typically used to treat depression, anxiety and compulsive disorders, but can sometimes help pedophiles control their sexual urges. SSRIs boost the amount of the messenger substance serotonin in the brain; this boost is thought to have a positive effect on a person's emotional state. Our team reported in 2003 that these medications significantly decreased sexual fantasies, sexual desire and compulsive masturbation in pedophiles. These drugs, however, have not yet been proved to work against pedophilia in a clinical trial that compares them with a placebo.

Other promising medications target the hormonal regulatory system that is governed by a duet of small regions at the base of the brain: the hypothalamus and the pituitary gland. In one of their hormonal collaborations, the hypothalamus produces something called luteinizing hormone-releasing hormone (LHRH), which in turn causes the pituitary to release LH. LH then prompts the testes to produce and secrete the male sex hormone testosterone.

Drugs such as leuprolide acetate, a so-called LHRH analogue, can block this sequence of events and thus dramatically decrease testosterone production, reducing it to castration levels. Patients with deviant sexual tendencies are significantly less apt to act on their impulses when using these medications. In some cases, these drugs and others enable patients to feel sufficiently unburdened to talk openly about their compulsive and often agonizing sexual fantasies and behaviors.

Ironically, successful treatment can bring about its own complications. Often helping men gain control over their deviant sexuality ends up forcing them to let go of a distortion that formerly propped up their self-esteem. As a result, patients confront a major personal crisis. At this point, a psychotherapist tries to help a pedophile find a suitable replacement for the emotional stability he had received from his pedophilic sexuality. But even then, the work is far from done. Most pedophiles must struggle to restrain their predilections for the rest of their lives.