Breeding sibling reptiles doesn't have a great effect to the health of the offspring like it can in mammals.
In fact you can breed several generations or siblings together without ill consequence. With the diversity of ball pythons it is easy enough to outcross them with unrelated animals. So inbreeding isn't necessarily necessary.
I believe this topic is well covered in VPIs "Pythons of the World Vol. 2" Read it, enjoy it, learn it.![]()