The five-lock authentication achieved by the 2023 study was not incidental to its findings; it was the precondition for all of them. Without confidence that the samples were actually Beethoven’s, none of the health findings, ancestry findings, or genealogical findings could be attributed to the composer rather than to some unknown individual.
The authentication method—comparing multiple independent samples to establish genetic concordance—is elegant in its simplicity. If you have five locks of hair from different collections with different histories, and they all yield the same genetic profile, either they all came from the same person or some extraordinary coincidence has occurred. The probability of the latter is negligible. And if that common genetic profile matches what you would expect for a nineteenth-century male of Flemish descent living in the Rhineland area of Germany, the attribution to Beethoven becomes even more secure.
This method has general applicability. For any historical figure whose biological material has been preserved in multiple collections—and there are many such figures, from Napoleon to Mozart to Abraham Lincoln—the multi-sample comparison approach can provide authentication that single-sample analyses cannot. The more independent samples that match, the more confident the attribution.
The caveat, of course, is that the method works only when multiple samples exist. For figures whose remains are held in a single collection, or for whom only one sample has survived, the authentication problem is harder. But for Beethoven, the combination of his fame, his death in a musically connected city, and the culture of relic preservation among nineteenth-century musicians meant that multiple locks were cut and distributed, ending up in different hands that preserved them through different circumstances over two centuries. This fragmentation, which might seem like a problem, turned out to be an asset: the diversity of the sample provenance made the authentication more robust, not less.