If a particular thing was very bad, avoidance might mean eliminating a whole group of related dogs from a breeding program or even an entire breed. (ashgi.org)
By now I'm sure you read over our health articles discussing breed related dog illnesses and if you haven't, I highly suggest you have a look. (all-about-great-danes.com)
The risk for fights is not lower between related dogs as compared to dogs that are not related; family members may fight each other once the younger pups have reached adolescence. (texvetpets.org)