Chimerism is a very rare condition caused by the fusion of zygotes (fertilized eggs) into a single form during early cell duplication. It is extremely rare, with only forty or so known human cases. It is somewhat more common in the animal kingdom.
Cognitive-behavioral therapy is an action-oriented form of psychosocial therapy that assumes that maladaptive, or faulty, thinking patterns cause maladaptive behavior and negative emotions.
Cognitive behavior therapy has been used to treat people suffering from a wide range of disorders, including anxiety, phobias, depression, and addiction. CBT is one of the most researched types of therapy, in part because treatment is focused on highly specific goals and results can be measured relatively easily.