The study of human twins in medical research.
D002823:Chorion / Q000502:physiology; D005260:Female; D030342:Genetic Diseases, Inborn; D005826:Genetics, Medical; D006801:Humans; D001523:Mental Disorders / Q000235:genetics; D011247:Pregnancy; D012042:Registries; D012106:Research; D012107:Research Design; D014427:Twins; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic