point mutation, or nucleotide polymorphisms.

the technique is whole genome scan for matching variations of single nucleotides.

with a few snippets, this wont work, with a large "input string" the variations at scale become increasingly exclusive.

this is akin to "late model ford" vs "1994 red ford explorer, with a dent on front left bumper, a deep scratch on the trunk, with one dim tailight."

or similarily, pixel variations baked into printer output, as identifiers linking a particular document to a particular printer.

more matching polymorphisms exclude similar individuals,until identical individual becomes apparent.