There have been articles(that I can't seem to find..-.-) about this. Cribbing is now thought to be genetic, meaning a horse has to be genetically predisposed to cribbing to be able to pick it up. A horse that does not have a relative(parent, grandparent, etc.) that cribs, will more than likely NOT learn this behaviour. However, a horse that DOES have a relative that cribs, has a higher chance of picking it up.
Some people do not believe this to be true, but I do. I worked in a barn of 40+ horses with 3 cribbers. There were horses stalled all around them for years in the same stall. Not a single one picked it up.