Training matters too don't get me wrong....But you've more chance of producing a goodun If you've got good breeding
You say Fox Isn't much test but some Lads (Not me unfortunately) Take there dogs out on Fox 5 or so days a week every week....Soon sorta the Good & Bad ones out.
A long long time ago people also put their dog's to Badger...Need a real game dog for that and I've heard about Staffys that made the grade
Butch