He has cerebral palsy (mild enough that he can walk, though wobbly). I wonder if his different feet sizes might contribute to his balance problems, as well.
More detail in case it might be related: He has ADHD and Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS is on the autism spectrum). We adopted him, so we don't know a lot of genetic history. Maternal side has history of polycystic kidney disease, high blood pressure and heart disease. He had genetics testing from a major university to rule out Fragile-X and other genetic symdromes.
1 me + 1 hubby + 4 kids + 5 goats + 3 pigs + 3 dozen chickens + 6 ducks = 1 crazy place
You might have a good hunch there, the body is not being used evenly and then other parts of the body over compensate. Consider seeing a pediatric chiropractor. They could check for leg lenghth discrepancy, hip alignment, spinal curvature, etc, and do adjustments as necessary. If one leg is shorter than the other, having a lift or other orthotic on that side would help hip alignment, which would help spinal alignment, etc. It seems logical, that if you work with the childs body while it is actively growing, then there is better chance for it to ajusts and compensate. Physical therapy might be something else, to strengthen the weaker parts of the body? I read a book about a super preemie who had brain damage that affected motor functions like cerebal palsy, and she had lots of physical therapy and large and small motor help and interventions. One they did was they put her good hand in a cast, and did intensive therapy with the weak hand. And she greatly improved in her abilities. I was trying to give an example, I hope you understand my idea.