But the combination of circumstances required to find identical twins in such a context is specific: ancient DNA must be recoverable from both individuals; both must be present in the same assemblage; and the assemblage must be analyzed by researchers conducting kinship analysis rather than focusing exclusively on population-level questions.

Prior to the Chichén Itzá study, ancient identical twins had been identified in a small number of other archaeological contexts using genomic methods.

Each case has attracted significant attention precisely because of the rarity of the finding and the specific human story it illuminates.

The Chichén Itzá case is distinctive for finding not one but two pairs of identical twins in the same specific archaeological context.

The probability calculation for this is illustrative even if approximate.