Thanks for the question. Interbreeding of a mother to an offspring does carry a high risk of genetic problems. It is possible that the pups will have problems, or that they will be born normal. Since she appears to be far along in her pregnancy, I wouldn't advise terminating the pregnancy at this point. I hope all goes well, and I recommend spaying/neutering, or keeping offspring separated once they are over 5 months of age to prevent future pregnancies.