Twin data available from national health examination surveys.
D000293:Adolescent; D002648:Child; D005260:Female; D006801:Humans; D007255:Information Services; D008137:Longitudinal Studies; D008297:Male; D010808:Physical Examination; D011247:Pregnancy; D012107:Research Design; D012494:Sampling Studies; D014427:Twins; D014481:United States; D014492:United States Public Health Service