They say that all dogs came from the wolf...so we have a wiener dog, great dane, and a collie. They look very different from each other. That right their says a lot to me about genetics...
Some say you can only breed as good as the sire and dam and I do agree with that... However, I believe that some think it is what they see in the sire and dam and that is partially true...but it is what we don't see that that we need to watch out for...that is why some breeders can breed a line or a strain of dogs that improve with every generation and another breeder can take the same dogs and take that line of dogs in another direction.
It is just as important to select the pups correctly as it is to start with the best breeding stock available...if not more so...
A good example would be...
one breeder sees a 6 month old puppy as very trashy treeing coons and running a deer for an hour running alone and culls him...
Another breeder has the exact same pup and he gets very excited with this trashy pup...he is thinking that he has an early starting star pup (natural) that wants game...has a good nose and can locate game and stick with it etc. etc... He keeps the pup in hopes of using him as a breeder to improve the bloodline...
This example explains a few reasons of many as to why we have so much variation in our hunting dogs...
Which is EXACTLY what makes this so rewarding to me... choosing the right genes out of a line can create a completely different animal quite quickly...