I don't know how many of you are aware of the different types of beta casein their are in milk. All milk has a substance in it called BCM7 (beta-caso-morphiene 7). It is an opiat, an addictive substance.
Milk is made up of 109 proteins and at position 67 there is a difference between A1 and A2 milk. A1 milk has a protein called histidine which allows the BCM7 out of the milk and into the blood stream. A1 milk tends to promote: Schitzophrenia, Autism, Diabetes and heart disease. A2 milk has a protein called Prolein at position 67 which prevents the BCM7 from getting into our blood stream.
Autistic children are supposed to have a casein gluten free diet. If they can find A2 milk, they can drink it without the negative side effects it normally causes.
Every individual of every mamallian species that has ever been tested (sheep, yak, human, waterbuffalo, camel, goat, etc.) except for cows are always A2. The Isle of Gurnsey in the English Channel closed its borders to the importation of other cows in 1798. Over 90% of the Gurnsey milk is A2. The more the breeds have been pushed for volume, the lower the percentage of cows come up positive for A2.
Mother Jones has a good article you may want to read on the subject.