I seem to remember reading somewhere a long while ago that horses do not tend to learn through 'copying' or modelling others' behaviours, so this fits. However it is amazing how many people think they do and get really freaked if there is a weaver or a crib-biter in the same stable block - like their horse might somehow 'catch' it.

I once heard Monty Roberts asked by a woman at a clinic what she could do to stop her horse crib-biting and basically he said 'nothing - we create them by the way we keep them' or words to that effect. She didn't like the answer - I think she thought a bit of round-penning might sort it out!

Here's something else to think about. I once bred a mare who cribbed, the owner did not keep a crib strap on the mare while she was in foal. That foal cribbed shortly after birth.
The mare was rebred and the mare wore the strap the whole time she was in the foal, the second foal never cribbed.
Same farm, lots of turn out, relaxed enviroment.

From what I studied in school, they seem to have learned it from their surroundings, now I hear of new research saying it is genetics.

http://www.thehorse.com/viewarticle.aspx?id=14706

But I think you can do so many things to help the problem as in changing the feeds or even adding new toys to distract them for doing this.

www.ValentinasEquineNews.com