Yes I did.
And I meant it.
The likes of the Kennel Club only allow you to call a dog a "pedigree" Jack Russell, if both its parents were on their register as pedigree JRs.
There's no way to get new blood into the breed.
This has been happening for many generations so, they are all mating with their close relatives.
If they are pedigree dogs I can trace their ancestry back to a very limited stock. The mother may not have been shagged by her father, but she was shagged by her cousin, and so were her grandfather, grandmother and great grandpa .
(If they are not pedigree dogs then they are off topic)