As we near session zero day my group is asking questions about ancestries. My question to you is regarding rare Ancestries. Not info about the ancestries themselves, but rather the (rare) tag.
I found this info (PC2) about uncommon ancestries and heritages, and rare backgrounds.

But does something like this exist for a rare ancestry? I was hoping the Ancestry Guide would have something.
As a Trait, the description of Rare applies to everything it is attached to, ancestory, spell, item, or other. You can find the full description at https://2e.aonprd.com/Traits.aspx?ID=683 but generally in non-PFS play it just means you should ask the GM before selecting it. In PFS play you will need to purchase a Boon.
Thank you, i looked at that table of terms but missed rarity because I was looking for rare specifically, and in the context of the box with the uncommon i posted.