Penn State's failure to report Sandusky's alleged crimes has outraged politicians and the public, but it's hardly a surprise to experts on such crimes. They say concealment seems woven into the very fabric of sex abuse.
In Scout's Honor, his 1991 book about sex abuse in the Boy Scouts, Patrick Boyle reported that for decades the scouts not only dismissed sexually abusive scoutmasters without informing police, but that their written policy stipulated that abuse files be kept secret "so that they cannot be subpoenaed in any legal action."
The scouts have since revised that policy but are still secretive about their abuse data, Boyle said.
Secrecy about sex abuse is not confined to institutions like the Catholic Church anxious to protect their public image, said Patti Levenberg, counseling coordinator for NOVABucks, a counseling agency in Jamison.
"Even a family has that same internal need to protect the institution" - the institution of the family, she said.
Many cases of incest and other familial assaults go unreported, Levenberg said, because mothers and children "don't want their institution crumbled" by the shame and financial hardship that might follow a criminal conviction.
Sex abuse within families is thought to be the most common type of molestation, with girls the more frequent target.
Fathers, stepfathers, and mothers' boyfriends "tend to control their victims more through their private access and family authority," according to former FBI Special Agent Kenneth Lanning, author of Child Molesters: A Behavioral Analysis, a text for law enforcement.
"Acquaintance molesters" - those who operate outside the family - tend to target boys, according Lanning, and they gravitate to youth groups.
Those who go after younger children will typically resort to "fun, games, and play to manipulate younger children into sex," he wrote.
"Those who prefer older child victims are more likely to take advantage of normal time away from their family, and then rely more on techniques involving ease of sexual arousal, rebelliousness, inexperience, and curiosity."
Though the Catholic Church's own data show that nearly 5 percent of American priests were credibly accused of abusing minors between 1950 and 2000 (about 85 percent of the targets were boys), it is difficult to measure how that compares with other large youth-serving institutions, such as public schools.
"Nobody knows who the king of abuse is," Boyle said last week. When scandal struck in the 1980s, "the scouts said their problems were no worse than society's as a whole. But we don't know society's as a whole."
In 2006, Shakeshaft remarked that a child was "100 times likelier" to be abused in a public school than in a Catholic parish - a statistic that Catholic bishops often cite.
But last week she said she had been referring not just to criminal sexual abuse but also to all the crude jokes, taunting, pinching, unwanted kissing, and jostling that public school youngsters may encounter from peers as well as teachers, coaches, bus drivers, and other adults.
"I rue the day I made that statement," Shakeshaft said.
She said up-to-date research on the nature and scope of child sex abuse remained poorly funded and sketchy. One area - sexual assaults by women - is little-studied and thought to be greatly underreported.
Pennsylvania lawmakers are calling for tougher mandatory reporting laws for child abuse in light of the Sandusky scandal, but child advocates say protecting children from predators before they abuse is still the foremost task - and perhaps the most difficult.
"How do you warn children about molesters who may be their teacher, coach, clergy member, therapist, or Internet BFF?" Lanning asked. "Young children are more likely to listen to what adults say, but less likely to truly understand. Older children are more likely to understand, but less likely to listen."
Teenagers need to understand that "their desire for freedom and autonomy may put them at greater risk."
Making children safe should rely less on dire warnings, Lanning said, "and more about involvement in their lives, communication, and love."
Contact staff writer David O'Reilly at 215-854-5723 or firstname.lastname@example.org.