Forensic Genetic Genealogy in Cold Case Investigations: Scientific Applications, Limitations, and Genetic Privacy

Conventional short tandem repeat (STR)-based DNA profiling has transformed forensic identification; however, its investigative utility may be limited when no matching profile is available in forensic DNA databases. Forensic genetic genealogy (FGG) addresses this limitation by combining genome-wide single-nucleotide polymorphism (SNP) analysis with genetic genealogy and traditional genealogical research. Investigative forensic genetic genealogy (iFGG) emphasizes the application of these approaches to generate investigative leads. Unlike conventional DNA profiling, FGG enables the investigation of distant genetic relationships, although its findings require independent forensic verification. This narrative review critically examines the scientific principles, methodological developments, forensic applications, and limitations of FGG, particularly in cold case investigations and the identification of unidentified human remains. It also evaluates challenges related to DNA quality, mixed DNA profiles, population representation, database accessibility, genealogical interpretation, and the reliability of bioinformatic analyses. Genetic privacy, including its implications for biological relatives, and associated ethical and legal considerations are discussed, with particular attention to the potential application of FGG in Türkiye. By integrating scientific, investigative, and ethical perspectives, this review highlights the distinction between genealogical investigative leads and forensic evidence and identifies the need for methodological validation, transparent governance, and appropriate safeguards for genetic privacy.