When I was a kid a buddy of my dads had a GWP that had gotten knocked up by a Doberman Pincer. The litter of pups that resulted from that mix had "bad" temperments. Eyes open only a few weeks and they were jumping up and snapping at the face of of kids. They would fight with one another until they were bleeding. The whole F'n litter was put to sleep for the safety of humanity. No joke.