doctorbadwolf
Heretic of The Seventh Circle
It is exactly what’s happening. Even if you look like the other parent ancestry, you are “actually” the other. No matter what, there is one ancestry that is your “real” ancestry.Also, regarding the Origins UA Mixed Species argument, the "One Drop Rule" accusation is inapplicable. It's not even a good metaphor. You don't have to like the rule, but don't misprepresent it with real world racist accusations. The One Drop Rule said if you had one drop of something, you are only that thing. That is not what is happening.

Which erases actually mixed ancestry.If a character was born of an Elf and a Half-elf parent, they are going to have the stats of either an Elf or a Half-elf, not a mix of both.
It's not racist to say the player has to pick one Species to represent their Species Abilities. Using that same logic, it's not racist for the child of an Elf and Human to have the species abilities of one of the parents. It is the same player choice for if the parents were an Elf and a Half-elf (unless the DM limited it further, like in Eberron.)
Half-elves in Eberron are predominantly born of half-elf parents, but it’s far from the only way half-elves exist in the setting, and nothing in Eberron stops you from using human or elf stats and saying “I’ve got a great grandparent who was Khoravar, but I don’t especially identify with that.” Or whatever.One could argue that Eberron's take on Khoravar half-elves is more problematic because in Eberron, all Half-elves breed true, erasing their human and elven origins. But we need to stop going down both those rabbit holes.
Again, this is not a thing in Eberron.Unless it is Eberron and the DM says you can't be an elf or a human, you can only be a half-elf, because half-elves breed true. But that is even closer to the One Drop Rule than the other position