lol at um all of the above, i had a rottweiler i know how bad the flatulants can be. My understanding is the same as Allan's there all related, but genes are naturally going to become more prominent in certain lines due to the even further concentration of those genes, where others would be removing certain genes by breeding out to non carriers. All the genes can be brought out from any line as there all there, but breeding to target will make better of them.