It’s more than just hereditary, because the first stage requires doing well on a broad general knowledge exam - if one doesn’t pass the first test, they won’t be given a chance at the second stage, regardless of their ancestry.

I see Sovann as wanting to become a Matriarch partly because she wants to have a say in her government but also so her family can continue with the privileges they’ve grown accustomed to, especially for the benefit of her younger daughter (who is in the 12-14 age range) and eventually her grandchildren.

I enjoy your comments, as they give me more food for thought!