Autosomal DNA analysis for relationship determination requires enough information across enough genomic positions to make statistical inferences about shared ancestry.

The technique used in the study was designed to maximize the useful signal from a minimal amount of starting material.

The result was enough information to compare against modern reference samples and to make statistical inferences about the degree of genetic relationship between the hair sample and Ernie LaPointe.

The comparison found shared genetic segments at levels and in patterns consistent with the stated family relationship.

What the technique cannot do — and what no genetic technique currently can do — is identify a specific individual with certainty from degraded hair alone.