For several months when my daughter was about 10 years old, she had bouts of ferocious blinking. I talked to her pediatrician. ("She's probably under a little stress," he said. "It'll stop.") I knew that fifth grade was turning out to be kind of a bummer, friendswise, and I made sure she and I had time to talk about what was on her mind. Even so--even being the informed, caring mother I think I am--more than once I caught myself saying to my daughter, "You're doing it again! Can't you stop that?!"

That's the thing about kids' nervous habits--they get on our nerves. Or, we worry that they signal problems. What do the experts advise? For the most part, they say relax. And bite your tongue when you're tempted to get on your child's case about an annoying mannerism.

Almost all growing children develop nervous habits from time to time. "Parents can help themselves by learning what's appropriate or common for kids at different ages," says Joan Hodgman, M.D., F.A.A.P., professor of pediatrics at the University of Southern California School of Medicine, in Los Angeles. "If your child's habit really concerns you, your pediatrician can see if there's any underlying condition. Then, you're wise to try to figure out what the habit means to the child. Is it a way to release tension, for instance? But don't use punishment to try to get rid of the habit."

"Parents may worry that these nervous habits signal serious problems. For the most part, though, the experts say relax"

Here's a when, why, and what-to-do guide to specific problems:

Thumb or pacifier sucking, rubbing the face with a favorite blanket (remember Linus?), twirling the hair, pulling earlobes, and fondling the genitals are all common self-comforting or self-stimulating behaviors in infants and young children. These are the ways they release tension or make themselves feel better. So let your baby suck, fondle, or twirl. Most children naturally abandon self-comforting habits by age 4 (although even older children under stress may briefly regress). Try to quash the behavior too soon or too brusquely--by repeatedly pulling away the thumb sucker's hand, for instance--and you're likely to make it more entrenched. If you're really going buggy at the sight of that thing in your kid's mouth all the time, offer gentle distractions--a toy to hold, or a hug if you've figured out he sucks when he gets bored or tired. "Start to lose the pacifier when your child is going on four," says Ordean Torstenson, M.D., F.A.A.P., a pediatrician with the Dean Medical Center in Madison, Wisc. "Tell her pacifiers and thumb sucking are okay when she's going to bed, but they're private, not so great when she's with people."

When your child is learning to speak, often her tongue can't wrap around those words as fast as her brain is coming up with them! Some degree of normal stuttering, say experts, occurs in up to 90 percent of kids between the ages of 1 1/2 and 5. Avoid supplying the words she's trying to say, telling her to slow down or start over, or correcting her. Give her time to finish, and be a relaxed listener.

It's harmless, so try to ignore it. School-age kids, and even preschoolers, often chew their nails. Neither the habit nor the fingernails look very attractive, but once kids get old enough to become concerned with their appearance--usually about age 10--nail biting usually starts to taper off. If a child is such a serious nail biter that her fingertips get raw and painful, the biting may be how she's releasing tension or stress. As with any nervous habit, suggests Joan Hodgman, M.D., F.A.A.P., professor of pediatrics at the University of Southern California School of Medicine, in Los Angeles, "try not to fix the child's attention on the mannerism. Don't talk about the nail biting, but see if there are pressures or stresses in her life that you can help alleviate."

On the parent-irritation scale, this one usually rates highest. "Get your hands away from your nose!" isn't going to elicit much cooperation on a permanent basis, but you can tactfully tell your child that nose picking in public isn't nice--and ask him if he'd like you to give a little secret signal if you notice him doing it. Kids usually pick their noses for the specific purpose of removing dried mucus that's tickling or making it hard to breathe. If he gets a lot of nagging on the score, the behavior can turn into a nervous habit. Stop nagging, encourage him to use petroleum jelly to soften any scabs, and wait patiently for the public nose picking to go away. It will.

A friend tells me her 7-year-old son went through several months of "eating oddly." At first, she couldn't put her finger on what it was, and asked him if he was having trouble with his food. Josh said no, he just had to chew every mouthful ten times. My friend said "oh," and let the matter drop. Which was wise. Many kids, especially between the ages of 6 and 10, develop favorite rituals like touching every fence railing, stepping on every other crack in the sidewalk, chewing a certain number of times. They're "magic spells" that a child uses to reassure himself, and although they may slow down your progress when you're trying to get somewhere, or may seem silly, they don't usually mean your child is especially anxious.

Many kids, especially between the ages of 6 or 7 and the early teens--and especially boys--will start furiously twitching in one way or another. You should know (as I should have known when my daughter was in her blinking phase) that such mannerisms can be involuntary. And they don't necessarily signal great stress.

"Most repetitive behaviors start out for a real purpose," says Ordean Torstenson, M.D., F.A.A.P., a pediatrician with the Dean Medical Center in Madison, Wisc. "The child needs to clear his throat or tosses his head to get hair out of his eyes. Then the behavior draws some negative attention, and unconsciously he does more of it. Stresses in his life then may accentuate the behavior."

The final word on our kids' nervous habits: Most of the time these too shall pass. "Don't let them drive you nuts," says Dr. Torstenson. "Or you might develop your own nervous habits!"