In more than five years of counseling and listening to sexual offenders of all ages, William J. Endy has heard a lot of memorable things, but one conversation stands out.

At the time, the clinical director of the Intermountain Sexual Abuse Treatment Center was treating sex offenders at the Utah State Prison. One seemed particularly depressed, and Endy asked why."I just heard that the guy who sexually abused me years ago is getting paroled," he was told. "But it gets worse. I also learned that the first guy I ever molested just got sentenced to prison for sex crimes."

Adolescents are responsible for about half of all molestation of boys and for 15 percent to 20 percent of the sexual abuse of girls. And more than half of all adult sex offenders report that they committed their first sexual offenses when they were adolescents.

Several factors may help to create a young sex offender. Most often cited is having been a victim. But experts don't agree on what percentage of sex offenders were victims.

A report by the task force of the Utah Network on Juveniles Offending Sexually suggests the number may be as high as 47 percent.

Endy, a task force member, views the statistics with caution. "It's significant, but from my experience treating an outpatient population, I'd say it's closer to 20-30 percent," he said. "It can be an excuse. Defense attorneys, I think, have caught on that it could be to the client's advantage to paint them as victims."

When a California prison was selecting inmates who were incarcerated for sex offenses to move into a halfway house, 72 percent said they had been molested as children. But when they were told they had to pass a polygraph test to participate, that number dropped to 28 percent.

Some sexual abuse is the product of curiosity and natural experimentation. And it's important for a parent not to overreact to a child's natural curiosity about sex.

To decide if it's unhealthy and unnatural, investigators look at differences in age, frequency, duration and the degree of intrusiveness.

"For some, sexual abuse is a method to exercise power and control over others," Endy said. "Kids may use power and control, sometimes sexually, to overcome feelings of social inadequacy."

"Significant exposure to pornography could be a problem," said Dave Fowers, Millcreek Youth Center in Ogden. "Children can get hold of a wide selection, but they can't process it. They have no experiential context. Even elementary school kids have access to materials if they want it. Parents should be alert to a child's materials that might be OK for adults but not for him."

"Dysfunctional families" may be a factor, Endy said. "Kids are impacted by problems in parents' relationship, their bad parenting skills, etc. You can abuse a kid without laying a finger on him: neglect, verbally, derisively. No bruises, but lots of scars. A dysfunctional family can increase a child's frustration and lead to sexual offenses."

Some children are also fascinated by "covert stuff and things that are implied," Fowers said. "A child can become obsessed with sex just because it's a big secret."

The report also cited low self-esteem, feelings of helplessness, the need for intimacy and cognitive distortions and irrational thought processes as possible factors.

Children are getting better at recognizing abuse, but it's complicated because not all sexual molestation is viewed by the victim as abusive and coercion plays a big part.

Baby sitters might bribe the children in their care with candy or by allowing them to stay up later.

"We naturally think of it as an unpleasant act, but what if the victim happens to enjoy it - say he's been told it's a `special game' baby sitters and kids play and it feels good," Endy said. "A skilled therapist isn't going to try to convince a child he's been traumatized. But a parent's reaction can be very strong and upsetting. A child can pick up on that."

Some things can tip a parent off that sexual abuse is occurring, but none of it is foolproof. Undue interest in sex is a warning, but experts caution parents not to overreact because childish interest is natural.

If a child presents himself or herself in a sexualized way, parents should ask questions. If a child suggests playing games that have sexual overtones, find out where he learned the game.

Inquiries should be made if a child shows a strong aversion to contact with an adult or adolescent or if he becomes suddenly moody and reclusive.

One woman learned her 5-year-old son was being abused when he kissed her inappropriately. Another noticed her child was constantly touching his genitals, both strong indications that something is wrong.

"There's a big temptation to look away from this, because it's unpleasant," Endy said. "But a lot of innocent children could be spared victimization if we stop and do something about it."