title: The human twin.
mesh_terms: D003071:Cognition / Q000502:physiology; D005260:Female; D006801:Humans; D008393:Marriage; D010551:Personality; D011247:Pregnancy; D012649:Self Concept; D012933:Social Identification; D012934:Social Isolation; D014427:Twins / Q000523:psychology*; D014430:Twins, Monozygotic / Q000523:psychology*