UK: Rottweillers violent ; Nuture or Nature ?

Well put it this way,if you ever hear of anyone being SERIOUSLY attacked or even killed by a dog it is always something like a Rottweiler, a Pit Bull, or a Japanese Akita etc. It is never a Labrador , a Springer Spaniel or Golden Retriever or a Border Collie is it? But some owners of the aforementioned "viscous" dogs will never admit to the fact that it does indeed seem to be inherent their nature.