Author ORCID Identifier
Date of Graduation
Eberly College of Arts and Sciences
Forensic and Investigative Science
Forensic genetic genealogy has grown in both popularity and controversy in recent years. The genetic information comes from large numbers of single nucleotide polymorphism (SNP) markers. Polymorphism variations can be traced through familial lineage, determining how closely individuals are related to each other based on the similarities and differences in SNPs within their DNA. Polymorphisms account for approximately 85% of human variation. Genealogy and ancestry determination companies trace the lineage of a person back through multiple generations using polymorphisms. As more individuals submit their DNA for analysis the genealogical profile databases continue to grow in size. Law enforcement uses genealogical determination companies to compare DNA evidence from an unknown source to the thousands of profiles readily available on such websites. Analysts can then determine possible relatives, hopefully leading to an identification of the unknown DNA samples. Companies such as GEDmatch have made identification possible. Law enforcement used the genealogy database, GEDmatch, to identify the Golden State Killer in 2018. Most of these companies explicitly stated that consumer information could only be used in limited situations by law enforcement. However, many companies allowed agencies access in additional situations, as well as subtly changed their terms and conditions to allow law enforcement increased access.
A DNA sample was submitted to AncestryDNA, Family Tree DNA, MyHeritage, and 23andMe for SNP analysis. Although the profile was from a known individual, for the purpose of this research it served as an unknown DNA profile found at a crime scene. Resulting SNP profiles were uploaded to GEDmatch to identify law enforcement accessible familial matches and assign numerical values to determine relationship strength. AncestryDNA Library Edition was used to search public records to build family tree clusters for these matches. From there, a family tree was constructed through which two of these clusters could be linked. This allowed for a union couple to be identified, and, in turn, the individual who committed the crime.
This research streamlines the investigative process with transparency, a practice not typically employed by private genealogy companies or law enforcement. This process was completed using only those samples approved by the individuals for law enforcement use, minimizing any ethical dilemmas, while addressing and evaluating controversial aspects like investigatory privilege, the use of discarded DNA, and other highly debated topics of forensic science within the legal system. This research aimed to create a reference for which those interested in investigative genetic genealogy could use as a guideline, supported via figure summaries, current regulations, possible setbacks, prospective budget and timeline, and clear examples of what resources are available and how they can be utilized.
Hester, Sarah, "An Assessment of the Forensic Aspects of Genetic Genealogy" (2023). Graduate Theses, Dissertations, and Problem Reports. 11774.