My dad had a black and white rat terrier that was a squirrel and mouser/rat killing machine... Great dogs... Her name was trixxie, he love that dog went everywhere with him..
I have a pair of JRT brothers, about 8 months old. My 2 teenage children are stubborn, get that from their mom, but the 2 Jack's defy any adjective to describe their stubbornness. The only other 4 legged animal that they do not want to kill is my other other dog, a 90 pound lab/mastiff. We have had a JRT before, and he was a handful. But 2 at a time is proving to be a little much.
No, they think he's their dad. They fight, run, bark, and generally raise he'll until dad gets up and puts an end to their fun. I could yell at them till my voice is gone and not slow them down, but one big woof from him and they STOP.