title: Scope and methodology of twin studies.
mesh_terms: D001789:Blood Group Antigens; D004200:Diseases in Twins; D004777:Environment; D005260:Female; D005826:Genetics, Medical; D006801:Humans; D008722:Methods; D011247:Pregnancy; D011584:Psychology; D011795:Surveys and Questionnaires; D014427:Twins; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic
chemical_list: D001789:Blood Group Antigens