What causes people to have a habit of biting their cuticles?

* Anxiety or stress

* Boredom

* A desire to keep the nails and surrounding skin neat and tidy

* A compulsive need to groom or pluck at the skin around the nails

* A fungal or bacterial infection of the nails or surrounding skin

* A physical injury or trauma to the nails or cuticles

* Nutritional deficiencies, such as a lack of vitamin B12 or iron