The personal fable is the adolescent's belief that he or she is highly special and unlike anyone else who has ever walked the earth. Colloquially, these individuals are known as "special snowflakes." In other words, the adolescent thinks that since others are so obviously fascinated by him (adolescent egocentrism), he must be a unique individual.
Unfortunately, the belief can have serious consequences.
In particular, the personal fable can cause a tween or teen to believe that nothing bad could possibly happen to someone as exceptional as herself. In other words, since she's so special, she must be invulnerable.
Some research has shown that belief in the personal fable and one's invulnerability is directly connected to common adolescent risk-taking behaviors, such as promiscuous or unprotected sex, use of alcohol or illicit drugs, as well as physically dangerous acts, such as driving without a license or driving recklessly or while intoxicated.
Belief in the personal fable should not be confused with having high self-esteem. Tweens or teens with low self-esteem usually still hold a version of the personal fable.