How difficult would it be to create a decision to change your culture that belong to one of your parents? For example: Your father is a northman and your mother is a riverlander, and it is a regular marriage. This means you would be born a northman: But let's say you want to be a riverlander, is that possible?
My primary interest, really, is to find a way to make a decision to become High Valyrian if at least one of your parents are High Valyrian themselves: The decision would require significant prestige and a parent being high valyrian. That, or owning a Dragon. With those restrictions, you won't have a ton of High Valyrians running around, but at least it's possible for the player to become one (outside of ruler designer or playing a targaryen dynasty) if they don't start off as one already.
My primary interest, really, is to find a way to make a decision to become High Valyrian if at least one of your parents are High Valyrian themselves: The decision would require significant prestige and a parent being high valyrian. That, or owning a Dragon. With those restrictions, you won't have a ton of High Valyrians running around, but at least it's possible for the player to become one (outside of ruler designer or playing a targaryen dynasty) if they don't start off as one already.