User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-170.235.245.52-20130523162121/@comment-3146930-20130523173655

It is said in the series that gods don't have DNA, meaning all that "God having children with another god, who is also their sister," really doesn't matter much. They are like different kinds of energy; sure they may have started at the same source but they are all different.

Also, you are kind of off with the Athena/Zeus thing. Zeus had eaten Athena as he heard one of his children would overthrow him. Athena lived however and began to grow inside Zeus' head until his head hurt so bad, he asked Hephaestus/Prometheus to split it open.