Identical twins too.
McFadzean
W A
WA
D000762:Anesthesia Recovery Period; D000769:Anesthesia, Inhalation; D000771:Anesthesia, Intravenous; D002675:Child, Preschool; D004200:Diseases in Twins / Q000628:therapy*; D006801:Humans; D008297:Male; D014429:Twins, Dizygotic