Three eight-year-olds.
D000124:Achievement; D000293:Adolescent; D001827:Body Height; D001835:Body Weight; D002648:Child; D002657:Child Development; D002675:Child, Preschool; D004777:Environment; D005260:Female; D006801:Humans; D007360:Intelligence; D007361:Intelligence Tests; D008297:Male; D010552:Personality Assessment; D010808:Physical Examination; D005082:Physical Exertion; D011247:Pregnancy; D012649:Self Concept; D014310:Triplets