dogs

Question
i know some one that breeds jack russels but the mum and dad of the pups are brother and sister will this affect the pup please wright bak xxx

Answer
Yes it's very bad and can result in many many genetic disorders.
Don't buy a puppy from this person.

for more info on a scientific study done on inbreeding please follow this link:

http://www.physorg.com/news138025054.html

There are many many excellent breeders out there, find a reputable one who does not in-breed.