Human locomation is surprisingly complex. Maybe not that surprising, what with roughly 20 bones and 30 muscles in a single foot. That doesn't even include the joints needed for motion and the muscles required to move your legs or swing your arms while you walk.

Allegedly some law enforcement uses gait analysis to identify and follow individual people on CCTV recordings. Gait has diagnostic value in some neurological conditions (like multiple sclerosis). Doesn't seem far fetched that a complex disorder like autism would also affect gait.