title: The Kaiser-Permanente Twin Registry.
mesh_terms: D000293:Adolescent; D000328:Adult; D002140:California; D002648:Child; D005260:Female; D005838:Genotype; D006801:Humans; D007354:Insurance, Major Medical; D008297:Male; D011247:Pregnancy; D012042:Registries; D012107:Research Design; D014427:Twins