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.
The specialty of behavioral and Cognitive Psychology addresses human problems from infancy/toddlerhood to older adults and serves individuals, couples, families, classrooms, groups and organizations/agencies; techniques used are applicable to most settings.