Address your children’s anxieties: it’s essential that you deal with the underlying causes of the behavior and think about whether there’s stress in your child’s life that you need to address. If you have an idea about what might be making your children anxious — a recent move, a divorce in the family, a new school, or an upcoming piano recital complete with the grandparents who pay for the lessons — make a special effort to help them talk about their worries. This is easier said than done for most kids, of course, but suggesting a patently ridiculous reason for the nail biting — “I know! You’re trying to sharpen your teeth!” — may prompt them to tell you what’s really going on.
Don’t nag or punish: Unless your children really want to stop biting their nails, you probably can’t do much about it. Like other nervous habits, nail biting tends to be unconscious. If the habit bothers you, set limits. “No nail biting at the dinner table”. The most important thing is to keep what’s basically a nuisance from escalating or becoming charged with emotion. If you pressure your children to stop, you’ll just be adding to their stress and risk intensifying the behavior.
Talk about breaking habits: Begin a discussion with your children about what nervous habits are and how it’s possible to break them.
Help your children become aware of the habit: Encourage your kids to become more aware of when and where they bite. Agree on a quiet, secret reminder for times when they forget — a light touch on the arm or a code word.
Offer an alternative: Suggest a substitute activity or two (Silly Putty for car rides, for instance, or a smooth stone to hold while reading), and then have your child practice the alternative habit for a few minutes before school or at bedtime.
Try — and try again: Explain to your children that different people respond to different techniques, and encourage them to try a variety of solutions if the first one doesn’t work.