The interesting tying about gods is that they like to bend the rules on birth sometimes. If we assume that male + femal = conception of child, then we can infer that Thaliak and Azeyma were the whole parents of both, because there is no way the siblings could otherwise share a common parent.

But then there are those religions where male gods have been known to give birth and others where conception occurs without a pregnancy and the child simply comes to be.