As far as their breeding methods they were just like some of the top breeders in the world. They picked a trait/traits and bred for them. In turn thy culled for what did not turn out that way. So when you breed for traits from within a family over time you will get those traits. If you choose to keep doing that and continue to pile up the losses. that part can get retarded.

thru selection you get what you want. Selection of the bad works the same as selection for the good. You pretty much get what you ask for. EWO