Scene Context: Lacking civil archives, the future society attempts to locate Les's descendants via his genome and genetic matches in a population registry.
Essence of the Phenomenon: DNA does not store a person's biography, but it preserves their hereditary footprint. As long as a lineage remains unbroken, it can be tracked via shared haplotypes, identity-by-descent (IBD) segments, and distant genetic relationships.
Scientific Basis: Modern genomics is already capable of identifying kinship and tracing family ties across massive datasets using IBD segments and shared haplotypes, even among distant relatives. Thus, the core concept of "finding a person's living footprint through their descendants" is firmly rooted in real science.
Current Limitations: Over millennia, lineages can break, heavily admix, or become statistically diluted. Therefore, achieving an instantaneous, civilization-scale search for descendants represents an engineering and computational extrapolation of modern genetic genealogy, rather than its exact current capability.