Even if twins were buried together or in the same cemetery, the chance that both would preserve enough DNA for genome-wide analysis, in a form where they could be recognized as related, depends on preservation conditions, sampling strategy, and the specific analytical choices of the research team.

Additionally, recognizing monozygotic twins from ancient DNA requires conducting kinship analysis — comparing the genomes of multiple individuals from the same context to look for relatedness.

If researchers are only analyzing one or a few individuals from a site, twin identification is impossible regardless of what the DNA contains.

The large-scale sampling of the Chichén Itzá chultún — 64 individuals, all from the same feature — is what made twin identification possible.

Finally, the analysis must be conducted with the specific goal of looking for high-relatedness pairs among the assemblage.