I think I finally found the real answer and truth why children cannot tolerate CASEIN and it's because they don't have the enzyme tyrosine hydroxylase to metabolize tyrosine that is found in large quantities in casein.
Tyrosine is the precursor of octopamine.
I personally have observe that asperger children very high functioning are still not capable of eating products containing casein or tyramine, and those people are the ones having the most challenge with social impairment problems.
Interestingly enough the absent of octopamine in invertebrates is directly connected to social impairment.
Andrea Lalama.