Causes of Nail Biting

If you asked a nail biter what caused his or her disorder, you’d probably get any number of different responses, from “I do it because I’m stressed,” “I do it because my hands are ugly,” “I just can’t seem to stop and I don’t know why I do it,” to simply a blank stare.

The fact is, no one really knows what causes nail biting. It’s a form of self-mutilation, and it’s closely related to OCD (obsessive-compulsive disorder) and dermatillomania (skin picking). Some researchers believe that it’s connected to body dysmorphic disorder – the same type of cognitive defect that leads anorexics to look in the mirror and see a fat person when the reality is that they’re practically skeletal. It could even be genetic – scientists have actually developed mice that engage in compulsive grooming, leading to bald spots where they’ve pulled out their fur. They did this by deleting a particular gene.


Nail biting, whatever the cause, is a repetitive behavior. It’s common in people who display other OCD-like symptoms, and it often runs in families, which lends support to the theory that it could be genetic. It seems that people do it because:

-They feel a need to be soothed. Biting their nails calms them, and reduces  feelings of over-stimulation.

-They need to be stimulated. That’s the paradox – people bite their nails when they feel the need to be soothed, and yet they also do it when they’re feeling bored and need stimulation. It may actually keep them from feeling distracted or bored.

-They want to look perfect. You’ve probably seen people that seem to spend hours looking at their hands. In winter, they may pull their gloves off, examine each finger, put the gloves back on, and then repeat the entire process over and over. Then at some point, they start to bite. And of course, what happens is that their hands end up looking worse, the more they try to fix them.

Essentially, it’s repeating the same behavior constantly, and it invariably just makes ugly nails look even worse.

Pathological Grooming

So, nail biting is essentially OCD behavior that manifests as pathological grooming. That means that normal grooming behavior is totally out of control. Ordinary grooming is driven by a desire to look good. An ordinary groomer will file his or her nails, push back the cuticles, and maybe apply a coat of polish. With a pathological groomer, the journey from identifying a grooming problem to correcting it doesn’t follow the normal channels. A normal groomer says, “I have a hangnail, or a chipped nail. I’d better get out the nail file or the clippers, deal with it, and then go about the rest of my day.” The pathological groomer says, “I have a chipped nail. I am stressed. I’d better bite it off, and then I’ll feel better.” Eventually, the chipped nail isn’t even part of the equation – it’s just “I’m stressed and I’ll feel better if I bite.”

How Does This Differ from True OCD?

OCD sufferers don’t want their compulsions – they’re simply unable to control them. No one likes washing their hands over and over, driving back home from work to make sure that they’ve turned off the stove even though they checked it three times before they left, or torturing themselves with rituals that are designed to ward off bad luck. Pathological groomers, on the other hand, do it because it makes them feel good. You bit off just the right nail in just the right way! Now doesn’t that feel fantastic?

It’s very hard to break a habit that makes you feel good. Think of it this way. If you have OCD, you’re thinking, “I don’t want to bite off my fingernails. But if I do it in just the right way, my mother won’t die of cancer.” If you’re a pathological groomer, you’re thinking, “I don’t want to bite off my fingernails. But I sort of do. It makes me feel good, even though I feel guilty when I do it.”

This is why it’s so much easier to stop biting your nails than to deal with true OCD behavior – you’re not trying to ward off something horrible. That’s why using acrylic nails, wearing gloves, using bitter polish and snapping rubber bands that you’re wearing around your wrist will help you to stop the behavior.

Back to the Mice

So, back to the causes. Remember those mice we talked about? Researchers at New York’s Weill Cornell Medical college discovered that mice that were bred to have a certain genetic mutation were compulsive groomers. Mice that had that mutation groomed to the point where they pulled out all the hair around their eyes. They couldn’t help it. Each and every mouse that was bred with that mutation became a compulsive groomer. They also exhibited signs of extreme anxiety.

Of course, you’re going to say that people are different from mice, and you’re right. But there are similar mutations that appear in people who groom compulsively. The good news is that just because you have that particular mutation, it doesn’t necessarily mean that you will develop the behavior.

Further, people who do have the genetic mutation can work to combat it.

You can choose to modify your behavior so that you don’t bite your nails, or you can simply choose to live with the nail biting and say to yourself, “I can’t help it; it’s genetic.” In the final analysis, it’s really up to you. After all, nail biting isn’t going to kill you. And if it’s the worst failing that you have, you’re likely better off than most of us.

The Final Word

You’re reading this because you don’t want to bite your nails. So stop. There’s help out there in the form of support groups, psychotherapy, and all sorts of online resources. The Nail Biter’s Toolkit is a great way to kick-start your journey toward better-looking, healthier nails. You don’t have to be embarrassed anymore by ragged nails and torn cuticles. If you really want to quit biting your nails, don’t obsess over what’s causing the habit, and don’t let genetics stop you.

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