By Rose Garrett.

As a parent, you know you have your work cut out for you. What with getting your kids washed, fed, and to school and back every day, it's a busy job. But when the child you're raising to be a healthy, happy adult suddenly can't seem to get his fingernails out of his mouth, or her knuckles from constantly cracking, it's enough to make any hard-working parent wonder what they're doing wrong. So just why do kids develop repetitive habits like hair-twisting and thumb-sucking, and what, if anything, can be done about it?

“When I speak to parents, we try to look at the underlying reason together to find out why they're doing it,” says Jennifer Trachtenberg, M.D., pediatrician, “Many times they’re doing it because they’re stressed out or nervous, and are doing it to self-sooth.” Chris Hayward, M.D., M.P.H., Professor of Psychiatry and Behavioral Studies at Stanford University, agrees: “In the ideal it is best if parents understand why the behavior has developed and address the underlying meaning or cause of the behavior... either with or without expert help.” In other words, the bad habit may not be the problem –it may simply be your child’s way of relieving underlying problems.

That’s not to say that every child with a hangnail habit is crying out for help. It may be as simple a matter as a distraction from boredom. So how do you know when your child’s habit is becoming harmful? “A good rule of thumb is to seek help if behaviors are interfering with functioning in some way in school, home, friendships, etc., or if they are clearly manifestations of other more serious problems,” says Hayward. Otherwise, your child’s bad habit may simply go away on its own, especially as she grows older and social pressures make her think twice about sucking her thumb, or biting her fingernails.

Until then, Trachtenberg recommends taking these steps:

Work with your child to identify the problem. Does he gnaw on his fingers when faced with a tough math problem? Does she crack her knuckles when nervous? Being conscious of when and why he does it will help your child control his habit.

Talk to your child about why you want them to break this habit, and try and help them identify reasons to stop. Simply imposing your own will is not going to get the job done: “They need to be internally motivated,” says Trachtenberg. For instance, encourage your child to think about how classmates will view her more unhygenic habits, like chewing on her fingernails.

Construct a specific plan, identify goals, and set up a rewards system for success.

Instill the message. Make sure that you reinforce and reward your child’s efforts by giving praise, and remember that your understanding and support are important in the difficult task of breaking bad habits.

The bottom line, says Trachtenberg, is to be “persistent and consistent. Do it as a partnership, and I think it should work.” As a parent, it's up to you to help your child break bad habits, and decide if there's an underlying problem that needs more attention. All it takes is a little bit of insight, understanding and discipline.