User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-68.140.72.32-20130322105618/@comment-3146930-20130323224057

It isn't that there blood is complicated, it is actually the other way around. Gods don't have DNA, so any offspring they have won't have any kind of DNA match to another. Even if demigods are all cousins as far as a family tree goes, there is no common DNA link that connects them all.