>>4448
as in allow parent/sibling marriages?
don't think you can define it for cultures, but in the religions files if you add the following to a religion tag, it will allow them. (pc_marriage is Parent/child, bs_marriage is Brother/sister
pc_marriage = yes
bs_marriage = yes
and you can add the following to give you zoroastrian relation mechanics, but it's probably best not to because it might give you zoroastrian events if you're adding it to another religion.
divine_blood = yes
you could try adding that to a culture tag but I don't know how well that would work