The extent to which a child should physically resist — yelling, biting, kicking — may depend on circumstances, experts say. Sabin said such tactics could enable a child to escape — a Utah girl last week struck her abductor and he ultimately released her — or could backfire if attempted in an isolated area where the abductor had no fear of being noticed.

John Mould, a special education teacher who has raised six children in the Philadelphia suburb of Ambler, said he's impressed upon them that resistance might be the best option. "Even when they're younger, it's well-documented that being loud and fighting is the thing to do," Mould said.

With children ranging from 12 to 21, Mould and his wife have gone through a steady process of granting each child increasing independence — accompanied by precautions.

"We let them know when we turn things over to them," he said. "Now that you can do this by yourself, here are the rules you should follow."

One recent complication, he said, was the anxiety prompted by the mass transit bombings in London, followed by warnings from Mould's wife that the children should be alert to terror attacks in public places.

"At this point, the list of things to be scared of gets so long that it loses credibility," Mould said. "Either the kids get a sense of paranoia or they say forget it — there are too many things to worry about."

Joe Kelly of Duluth, Minn., whose experience raising twin girls propelled him to the leadership of an organization called Dads and Daughters, said parents face constant challenges as they try to instill prudence, but not fear, in their children.

"There's a lot of fear-mongering out there," he said. "You wonder how many of the decisions you're making in your parenting are coming out of fear."

Kelly recalled letting his daughters, now 24, take the bus unescorted for the first time as preteens heading to ballet lessons.

"There was a part of me that was terrified," Kelly said. But "they'd proven themselves to be responsible; it wasn't likely they would do something foolish. That doesn't erase the risk, but you can't encourage them to live their life in fear of reality."