The reasons for eating fingernails include emotional abnormalities, behavioral imitation, stereotypical behavior, etc., as follows: First, emotional abnormalities: caused by some anxiety, tension, especially in children, if children are very nervous, scared, more internal conflict, they will subconsciously chew their nails, using this method to relieve the internal conflict, relieve tension, anxiety emotional problems. Second, behavioral imitation: love to eat fingernails may be caused by bad imitation, especially when small, children watch television or imitate the children around them to eat nails, but also this imitation behavior, eventually leading to the problem of love to chew nails. Third, stereotypical behavior: there may be a stereotypical behavior caused by bad habits, such as from childhood already have love to eat fingernails behavior, he may not feel anxiety, nor by others, but they repeatedly appear this behavior, it is possible that a bad habit or stereotypical behavior.