So apparently, according to tradition the twin that is conceived first is believed to be born last, and there are folk explanations like “The first conceived attaches to the uterus first, so is more firmly stuck”. And so the later-born is considered oldest due to having been conceived first, even though that is not even a thing that can happen in the case of identical twins.
Still tracking down a decent history of the phenomenon, but it’s an interesting start.
So apparently, according to tradition the twin that is conceived first is believed to be born last, and there are folk explanations like “The first conceived attaches to the uterus first, so is more firmly stuck”. And so the later-born is considered oldest due to having been conceived first, even though that is not even a thing that can happen in the case of identical twins.
Still tracking down a decent history of the phenomenon, but it’s an interesting start.