The detection of anomalous extra-spinal left-right skeletal length asymmetries 
in the upper limbs, periapical ribs, ilia and lower limbs of subjects with 
adolescent idiopathic scoliosis (AIS) raises questions about skeletal bilateral 
symmetry of vertebrates in health and disorder, its origin and control. The 
vertebrate body plan externally has mirror-image bilateral symmetries that are 
highly conserved culminating in the adult form. The normal human body can be 
viewed as containing paired skeletal structures in the axial and appendicular 
skeleton as 1) separate left and right paired forms (eg long limb bones, ribs, 
ilia), and 2) united in paired forms (eg vertebrae, sternum, skull, mandible). 
Each of these separate and united pairs are mirror-image forms--enantiomorphs. 
Left-right asymmetries of growth plates (physes) may cause (1) in long bones 
length asymmetries, (2) within one or more vertebral physes putative growth 
conflict with distortion as deformity, and (3) between ribs and vertebrae 
putative growth conflict that triggers thoracic AIS suggesting preventive 
surgery on spine and ribs. There is evidence of a possible role for 
environmental factors in AIS development. Genes and the environment 
(nature/nurture) may interact pre- and/or post-natally to explain both the 
deformity of AIS and its association with widespread anomalous skeletal length 
asymmetries. If substantiated there may ultimately be a place for the prevention 
of AIS in some subjects.