DNA Database Utility in Resolving Complex Incestuous Paternity Disputes

Abstract

Incestuous paternity investigations are considered among the most analytically and ethically complex challenges in forensic genetics. Extensive allele sharing occurs among family members and close biological relatives. Mutations in short tandem repeat (STR) markers, together with the concealment or frequent absence of key family members, can interfere with reliable paternity interpretation and increase the risk of false inclusion or exclusion. This study describes a legally significant forensic DNA case, where the use of the national DNA database revealed unexpected paternal candidates, ultimately resolving a highly complex case. Initial autosomal STR profiling using AmpFlSTR™ Identifiler™ Plus and GlobalFiler™ multiplex systems indicated non-exclusion of an alleged father (AF1) accused of sibling incest, despite a single-locus mismatch consistent with mutation. Subsequent blind comparison within the DNA Database identified a second related individual who also could not be excluded as the biological father (AF2). Further investigation, including Y-chromosomal STR analysis and expanded testing of multiple maternal relatives, ultimately established a third individual (AF3), a maternal nephew, as the true biological father without mutational inconsistencies. These findings highlight the essential role of mutation-aware interpretation, comprehensive kinship analysis, and forensic DNA databases in accurately resolving complex incest-associated paternity disputes and preventing wrongful judicial outcomes.