http://www.bbc.co.uk/blogs/wondermonkey/2011/11/bred-to-destruction.shtml I found this link to quite an interesting article!! I've always wondered about inbreeding when it comes to thoroughbreds and how in other breeds of animal you get deformaties and other things going wrong but it doesn't seem to affect the racehorse in the same way. I know very little about breeding but I do find it fascinating about the selection process and whether this is ever taken into account! I'm sure it must be and it can't be as simple as mating the two best horses?
I'll refer you back to this. It may help. http://www.not606.com/showthread.php/90503-Ask-PN-October-2011?p=1433733&viewfull=1#post1433733
I saw that article, and have commented on it as you can see. The saying, as far as breeding goes, is "breed the best to the best and hope for the best". Sometimes it works (Urban Sea & Sadler's Wells), but more often than not it doesn't. I'd be in favour of restricted book sizes for stallions and for a grading programme to be put in place as they have in Germany.
I think he was from over there somewhere judging by his accent - he was teaching me how to shoot clay pigeons so had a 12-bore in each hand. Scary figure