His mom would be a Goddess too.I just thought of a crazy possibility that might be true. What if Qetesh is the mc's grandmother & his mom is her lovechild fathered by Nergal?
Erevi said beings that powerful need a host body to remain in the Human Realm. So, if the mom is a Goddess (Qetesh or her daughter) she would have needed to possess a body to get pregnant and give birth.
One of the Priestess would have to let MC mom posses her body to conceive the MC. If she remained in the body during all the Pregnancy or not is another variable.