Chapter 4 A Glimpse into Genetic Genealogy – Identifying Unknown Persons and Generating Suspect Leads in Violent Crimes Vanessa Virdiramo, Muhammed Talal Shaikh, Emma Wolfram Traditional genealogy has been studied for centuries, where documentary records (e.g. historical and medical) and oral histories have been used to trace families back through history (Plemel, 2019). Due to advancements in direct-to-consumer (DTC) genetic testing and related technologies, however, the field of genetic genealogy has grown exponentially in recent years and individuals are now able to find relatives through shared DNA using at-home kits (Kennett, 2019). Genetic genealogy is based on the philosophy of genetics, which encompasses the study of heredity and genes, and is the process by which heritable traits are passed down unchanged from generation to generation (Alberts et al., 2015). The more closely related individuals are, the more DNA is shared between them. As such, it is now possible to learn more about long-lost relatives and ancestors and assess the risk of genetic illness, among other things, using genetic genealogy methods. Given these capabilities, these techniques have recently gained popularity among law enforcement agencies for identifying unknown individuals and generating suspects leads in criminal investigations using DNA. In 2019, direct-to-consumer (DTC) genetic genealogy databases were used to identify suspects and missing persons in over 50 cold cases, many of which were unsolved for decades (Kennett, 2019). Genetic genealogy and DNA databases have received an enormous amount of public attention throughout the years, however, this has sparked a controversial debate regarding the use of these methods for law enforcement purposes. This chapter describes the fundamentals of genetic genealogy and DNA databases, the application of DNA databases in forensic investigations, the ethical and privacy concerns regarding these methods, and the laws set in place to prevent 59 Are We There Yet? The Golden Standards of Forensic Science the misuse of DNA database information. As well, there are numerous missing persons and cold criminal investigation cases to support this information. How Genetic Genealogy Works As aforementioned, genetic genealogy uses a combination of traditional genetic genealogy methods such as reviewing historical and/or medical records, and genetic analyses to examine family history (Plemel, 2019). To do so, hundreds of thousands of single nucleotide polymorphisms (SNPs) are analyzed, which are variations on particular locations in an individual’s autosomal DNA (atDNA) sequence (Mallett, 2019). Unlike other genetic markers such as mitochondrial DNA (mtDNA) and Y chromosome DNA, autosomal DNA (atDNA) is a type of DNA that is inherited from all ancestral lines and is passed on by both males and females (Mallett, 2019). Each individual has 22 autosomal chromosomes possessing two copies of each one: one inherited from their father, and one inherited from their mother (Greytak et al., 2019). Each pair of parental autosomal chromosomes is recombined to create a new chromosome that is passed on to offspring (Greytak et al., 2019). Thus, SNPs from atDNA of any two individuals can be analyzed, regardless of their sex, to determine whether they are related and by what degree. The unit of measurement for these DNA segments is centimorgans (cM), which is a measure of genetic distance and probability of recombination (Mallett, 2019). The atDNA is analyzed for segments of identical DNA above a particular length (five to seven cM), in order to determine the amount of DNA two individuals are likely to have inherited from a common ancestor (Mallett, 2019). When two individuals possess identical nucleotide sequences within their shared DNA, it is said to be identical-by-descent (IBD) (Greytak et al., 2019). Nucleotides that are closer together on a chromosome are more likely to be inherited together, while nucleotides that are further apart are more likely to be separated by recombination (Greytak et al., 2019). Recombination is the process by which pieces of DNA are exchanged between multiple chromosomes or regions of the same chromosome (Clancy, 2008). As a result, the more closely related the compared individuals are, the longer the shared segment of DNA on their chromosomes that is IBD and vice versa (Greytak et al., 2019). 60 A Glimpse Into Genetic Genealogy INHERITANCE OF DNA SEGMENTS ON A SINGLE CHROMOSOME Image by Vanessa Virdiramo Long stretches of DNA are broken-up by recombination of DNA over generations. The more closely related individuals are, the longer the length of shared DNA segments that are identical-by-descent (IBD). The more recombination events that take place, the shorter the shared IBD segments become, and the less related the individuals are. The unit of measurement for the IBD segments is centimorgans (cM). An example of inheritance of DNA segments is shown above. Each length of IBD segments are illustrated by shaded boxes to give the total amount of shared DNA amongst the 22 autosomes. In the image, full siblings share the most DNA and first cousins share the least DNA. 61 Are We There Yet? The Golden Standards of Forensic Science Genetic Genealogy Databases There are several prominent direct-to-consumer (DTC) genetic testing companies on the market, including 23andMe, AncestryDNA, MyHeritage, and FamilyTreeDNA. The goal of these companies is to provide members of the public with information regarding their genetic heritage and likelihood for genetic diseases. These direct-to-consumer genetic testing company databases contain DNA from individuals who have willingly uploaded their DNA for the purpose of obtaining information regarding their ancestry. There is a combined total of approximately 28.5 million DNA profiles of individuals in all DTC genetic testing databases (Greytak et al., 2019). The genetic tests are performed on DNA microarrays which analyze more than 600,000 atDNA SNP markers scattered across a genome (Kennett, 2019). A single DNA profile can cost around $120 to $170 USD and requires the use of an at-home DNA kit (National Academy Press, 1992). Most kits consist of a three-step process of spitting in a tube, swabbing the inner cheek, and scraping the inner cheek (Greytak et al., 2019). Following the completion of this process, the DNA kit is submitted for analysis and the results are typically emailed back to the individual who completed the sampling process. To utilize and compare the data originating from different companies’ DNA databases, users can upload their raw genotype data to third-party companies, such as the DNA database GEDmatch (Tillmar, 2020). This is a public database, whereby individuals can compare their raw DNA data results from DTC genetic testing companies to DNA data files from different DNA testing companies (Greytak et al., 2019). Unlike DTC genetic testing companies, this company does not require a cheek swab or spit kit (Novroski, 2019). This publicly available database along with DTC genetic testing databases, allows for recreational genetic purposes but also for law enforcement use. Application of Genetic Genealogy in Forensic Investigations In the case of forensic investigations, genetic genealogy can be used to identify unknown remains or to generate suspect leads in violent crimes. This method takes advantage of genotype data generated from hundreds of thousands of DNA markers, as well as private and public DNA databases to trace the relatives of an unknown sample, typically obtained from a crime scene. 62 A Glimpse Into Genetic Genealogy Investigators can use a DNA sample obtained from a crime scene and compare it to publicly available open-data personal genomics DNA databases like GEDmatch, or direct-to-consumer (DTC) genetic genealogy services like 23andMe, FamilyTreeDNA, or AncestryDNA. The most utilized genetic genealogy database by law enforcement is GEDmatch. This is because DTC genetic genealogy services have prevented access to law enforcement (Greytak et al., 2019). In fact, AncestryDNA and 23andMe do not allow law enforcement agencies to access their databases unless required by valid legal purposes (Kennett, 2019). In March 2019, FamilyTreeDNA revoked all access to non-US law enforcement. The only way to obtain ancestral information from these DTC genetic genealogy testing databases is by submitting a sample via a cheek swab or spit kit for testing on an SNP microarray (Novroski, 2019). In order for investigators to compare a DNA sample obtained from a crime scene to known DNA profiles uploaded to the publicly available DTC genetic genealogy websites, they must create their own DNA kit for submission (Novroski, 2019). This DNA kit must look at the same loci of DNA as the DNA kits from the ancestry websites, since a suspect does not have the opportunity to or may not be willing to spit, scrape, or swab (Novroski, 2019). Once a DNA kit is made, investigators generate a DNA profile and upload this information to a public database such as GEDmatch. From here, potential familial relationships between the forensic sample and service users can be determined, or the identity of the individual whom the forensic sample belongs. If potential relatives are indeed found, a family tree can be constructed and the suspect pool can be drastically reduced to a region, family, or single individual. The caveat of forensic genetic genealogy, however, is that it can only be used in forensic investigations when all other investigative techniques have been exhausted (Novroski, 2019). All investigative techniques have been exhausted when an unknown profile of a potential suspect of a violent crime has been uploaded to the Combined DNA Index System (CODIS) and there was a failure to produce a confirmed DNA match (United States Department of Justice Interim Policy Forensic Genetic Genealogical DNA Analysis And Searching, 2019). Genetic genealogy may also be used if no leads have been found regarding an unidentified individual after all relevant information has been uploaded to the National Missing and Unidentified Persons System (NamUS) (“United States Department of Justice Interim Policy Forensic Genetic Genealogical DNA AnalysisAnd Searching,” 2019).