Two Sides of the Double Helix: From Tracing Roots to Solving Crimes

In a previous post,  The Joy of Researching our Family History: Genealogy for Beginners,  guest author, Tara Shymanski, shared her personal and professional interest in researching family histories.

In this post, I will explore the fascination with personal DNA testing with a brief overview of the potential benefits and risks of testing for family research.  William Anhorn has thoroughly explored recent developments in Forensic DNA and given permission for us to reprint his article.

Growing Interest in Family History

Interest in researching our family history has grown in recent years due to a combination of factors:

• accessibility of online data bases
• a desire to preserve family history for future generations
• knowledge of family medical history can assist in the assessment and diagnosis of disease
• TV programs such as "Finding Your Roots" and "Who Do You Think You Are" have popularized genealogy by presenting compelling personal stories
• in our disconnected world people want to understand where they come from and have a deeper sense of belonging.

As part of family research, many people are seeking DNA testing to determine their ethnic background. 

What is DNA?

For a quick explanation (and review) of DNA  (Deoxyribonucleic acid) -- view this video.
What is DNA?  NHS England Genomics Education Programme  

What is DNA Testing?

First, there is a difference between medical genetic testing and that done as part of genealogical research.  

Genomics is "the study of an organism's genome - its genetic material - and how that information is applied."

Genetics is "the study of genes and their roles in inheritance ... the way that certain traits or conditions are passed down in the genes from one generation to the next." 

NHS England's Genomics Education Programme 

Genealogical DNA testing is explained by Ancestry.ca

A simple saliva sample, which contains cheek and immune system cells, is all that is required for an analysis since every cell in your body contains your DNA and your unique genetic code. There are several different types of genetic tests, but all of them begin by extracting your DNA from the cells in your sample and preparing it for analysis.
What is genetic testing?

Further, Ancestry explains three types of genetic tests and what is revealed by each.

• Mitochondrial DNA (mtDNA) A test of DNA inherited from the mother
• Y-DNA. Test of the Y chromosome (only in men) showing information about the paternal side of the family
• Autosomal DNA. Examines the genome and undercovers information about the maternal and paternal members of the family tree. 

Benefits of Genealogy DNA Testing

The first obvious benefit is discovering one's ethnic origin and establishing a sense of connection to ancestors.  Other benefits are more specific:

• finding living relatives
• adoptees identifying biological family members
• learning more about medical history

Risks of Genealogical DNA Testing

The most personal risk is uncovering an unexpected and emotionally distressful discovery such as misattributed parentage or unknown siblings.  Such discoveries can cause significant family disruption.  

Another risk is related to privacy.  The company could experience a data breach exposing highly personal and sensitive information. 

NOTE for a review of the data breach of 23andME see Resources.

Any health reports provided by consumer ancestry sites are not a substitute for clinical-grade genetic testing and should not be used to make medical decisions without consulting a genetic counselor or doctor.

Another major concern is that your DNA profile (and by extension, the DNA of your close relatives) could be used by law enforcement in criminal investigations, often without your direct consent, by searching through the company's database.  William Anhorn has explored this topic in detail and his article is reprinted (with permission)

I will add an opinion based on personal family research.  Digging into the past can be a violation of ancestral privacy.  Since deceased ancestors cannot give consent - do we have the right to know about their 'secrets' or 'sins of the past'?

William Anhorn

The Use of Forensic DNA

Excerpt from The Importance of Grandparents - From a Genealogical Perspective (or Why I Treat my Wife Like Royalty)  
Published February 26, 2023 by William Anhorn. Used with permission.

One of the  more recent developments for those who are interested in genealogy and creating their own family tree is the emergence of DNA testing and a more dramatic offshoot of this process - forensic DNA.  It seems that hardly a week goes by without a newspaper report indicating that a "Cold Case" has been solve using advanced DNA matching, which has led to the arrest and conviction of the perpetrator of the crime.  Even more fascinating is the conclusive identity of a criminal responsible fora murder (as an example) who has since passed away.  Or the exoneration of a convicted felon after years behind bars.  The collection of DNA evidence at a crime scene and the storage and cataloging of this evidence for future reference has resulted in many cases being solved long after the event. 

Although the amateur genealogist will seldom solve a “case” in this fashion, a basic understanding of DNA profiling and forensic DNA may be a helpful resource. The proliferation of sites that offer DNA testing as a tool for genealogical inquiry make this aspect of research readily available. 

What is Forensic DNA?

Forensic DNA also known as DNA “profiling” is the use of DNA analysis techniques to identify and compare DNA samples collected from crime scenes, suspects, victims and other sources. It involves the extraction, isolation and analysis of genetic material from biological samples such as blood, saliva, semen, hair and tissue, typically found at a crime scene. Even the most minute sample can be used for this purpose. Forensic DNA analysis has become a valuable tool in criminal investigations because DNA evidence can be used to identify suspects, exonerate or eliminate innocent individuals, link crimes together and establish an important timeline of events.

DNA profiling can also be used in paternity testing, identification of human remains and the investigation of historical cases. For example, the remains of a Canadian soldier from WWI were recently discovered in France. Through an exhaustive process using DNA recovered from the site, the identity of the soldier was determined and, more importantly, living family members were identified and contacted and the mystery surrounding his disappearance and death was finally resolved, bringing closure for the family.  This later aspect of DNA profiling has created a new area of study or discipline known as “forensic genealogy”.

There are countless unknown soldiers from WWI whose bodies have never been recovered. Many countries that participated in the Great War established memorials or monuments dedicated to these unknown patriots, including the cenotaph in London, England and the tomb of the Unknown soldier in Paris, France. One of the more impressive memorials is the Menin Gate in Belgium, where thousands of unknown soldiers are memorialized with their name engraved on a marble wall.

The analysis of forensic DNA involves comparing DNA samples from different sources to determine if they match. This is done by examining specific regions of the DNA molecule called “markers”, which are unique to each individual. If DNA profiles match, based upon probability algorithms, it is highly likely that the two samples come from the same person or closely related individuals. If they do not match, then the samples come from different individuals or from completely different genealogical families. The key to this branch of science lies in the fact that as “human beings” we all have, much like a fingerprint, a unique DNA molecular profile, which we have inherited from our parents and grandparents and other antecedents. This is referred to as “autosomal DNA matching or sequencing”. It is here that genealogy and science intersect, with amazing results. But how does it work? Simply put, it is in our “genes”!

All living species have a unique set of chromosomes. A chromosome is a thread-like structure made of DNA and protein molecules found in the nucleus of a cell. Chromosomes carry genetic information in the form of genes which are segments of DNA that provide a special code of specific proteins or RNA molecules. In most organisms, chromosomes exist in pairs, with one chromosome from each parent and they are responsible for the transmission of genetic information from one generation to the next during reproduction. Each species has a different number of chromosomes and the shape and size of these chromosomes can vary. Humans are unique in that the human cell has 23 pairs of chromosomes for a total of 46 chromosomes in each cell, except for the sperm and egg cells which only have 22 individual chromosomes.

What is an autosomal DNA match?

An autosomal DNA match is a person who has a shared genetic sequence on a numbered chromosome that may indicate at least one common ancestor. When we talk about DNA matching, we are almost always referring to autosomal DNA matches. An “autosome” is one of our 23 numbered chromosomes. We have two copies of each chromosome. One copy is the maternal copy or from the maternal side of the family (mother) and the other copy is the paternal copy, which is from the paternal side of the family.(father).

Each person inherits 50% of their DNA from their mother and 50% of their DNA from their father. When we consider DNA matching or profiling from a genealogical perspective, there is a rather interesting anomaly, which results in forensic genealogy being more of an art form than a science. 

The 50% of the DNA that is inherited from the mother is made up of half of the mother’s DNA and a random percentage or segment that has been passed down on the maternal copy of each autosomal chromosome. This random segment has been passed down through multiple generations. The same occurs with respect to DNA inherited from the father. In this manner, everyone has a unique connection to their ancestors from the past and from the standpoint of the amateur genealogist, this opens up a new and fascinating aspect of inquiry. But herein lies the interesting anomaly!

Even though half of our parents’ DNA is inherited in relatively random fashion through a process called recombination, large clumps of DNA are passed down from multiple generations, both from the maternal side and paternal side, going back multiple generations. These clumps of DNA are called DNA segments.

Let me explain.

When we consider the DNA that we inherit from our ancestors, the only quantity that we can be certain of is that we receive half of our autosomal DNA from each parent. Beyond parent-child relationships, experts tend to talk about averages or statistical probabilities, when analyzing or comparing DNA samples. These figures vary because our parents didn’t necessarily pass on to us equal portions of the DNA that they received from their parents.The level of variation is driven by the number (and location) of crossover events that occur when the ova and the sperm cells are created. 

For instance, we receive an average of one quarter of our DNA from each of our four grandparents and an average of one-eighth of our DNA from each of our eight great-grandparents and so on and to a lesser degree from each earlier generation of grandparent. 
From a genealogical perspective, parents are one generation back. Grandparents are two generations back. Great-grandparents are three generations back, and so forth, at least in theory, infinitely. 

For families who have a long recorded history where information is available in the form of original source material (i.e. birth records, marriage records and other confirmed and reliable sources), it is not unusual for a family tree to go back multiple generations. For example, it is not uncommon for a family tree to go back 20 generations or more. This is particularly true of famous families (the most obvious example is the British Royal Family)  which have become the subject to intense scrutiny and academic research.

An interesting resource:  How Big is Your Family Tree

References

Family History DNA Testing: Discover Your Roots

Discover how to delete your 23andMe data, protect your genetic information, and remove your personal DNA profile with this comprehensive guide.

What is DNA?
NHS England Genomics Education Programme

Resources

Genealogy Foundation
Ethics of Exploration: Privacy and Consideration in Genealogical Research

Genomics
Helping save lives through genetic profiling: researcher advocates for increased education, training in genomics.

The emerging field, which has become increasingly significant in nursing since the Human Genome Project sequenced the entire human DNA in 2003, is vital to precision health care, and Andrea Gretchev is compelled to contribute to the growing body of evidence to support this.

Pharmacogenomics
As the author of an open-access textbook called Precision Healthcare: Genomics-Informed Nursing, Andrea Gretchev is well-qualified to consider ways to add components about genomics into nurses’ education. The book was written for a course at Georgian College by the same name. She’d like to see all nurses educated to probe more deeply into patients’ histories to consider risk factors, the potential effects of genetic disorders and how they could affect health outcomes.

Canadian Nursing and Genomics
There are an estimated 440,000 nurses across Canada, who are responsible for providing safe, competent, and ethical care, as well as promoting health and social justice for Canadians.  Advances in genomic technology, including increased understanding of genetic risk, have contributed to the emergence of precision health. Precision health is true personalized care, incorporating genomic information to tailor clinical recommendations and management to the individual patient.  Nurses with genomic literacy will enhance the clinical utility of genomics by facilitating the mainstreaming of genomic medicine across primary, secondary, and tertiary care sites, supporting individuals and families, and addressing important ethical issues such as equity of access.

Data Breach 23andME

In October 2023, 23andMe, a company that provides direct-to-consumer genetic testing and ancestry services to individuals globally, confirmed a data breach that affected almost 7 million of its customers.

Backgrounder: Summary of joint investigation into the data breach of 23andME by the Privacy Commissioner of Canada and UK Information Commissioner.

23andMe 'failed to take basic steps' to protect private information, investigation finds.
Hackers accessed nearly 7 million customers' data in 2023 breach.
Darren Major. CBC News. Last updated June 17, 2025.

Author

Maureen Osis
Maureen retired from her career -- first as a Gerontological Nurse and then a Marriage/Family Therapist in private practice working with mid-life and older adults. Maureen published numerous articles and books, related to her professions. She is a member of CALL because she is passionate about learning. She is a volunteer with CALL, doing social media and the primary author of the blog, because she likes to face new challenges.
Maureen developed an interest in researching family history when she was semi-retired in 2012.  Her mother, the last survivor of 13 children, was alive to share stories and talk about some of the discoveries.  

Guest Author

William Anhorn, K.C. ICD.D
William J. Anhorn was born and raised in Medicine Hat, Alberta and graduated with a Bachelor of Arts degree (Political Science) from the University of Calgary and a Bachelor of Laws degree from the University of Alberta. 

He returned to his hometown of Medicine Hat in 1976 and practiced law for over 35 years as a Senior partner with the Law firm of Pritchard and Company. He retired in 2012 and he and his wife Joan Elaine Anhorn (Medlicott), a retired teacher, continue to reside there. 

He is a member of the Medicine Hat Genealogical Society and past Chairman of the Historical and Heritage Resource Committee of the Medicine Hat Exhibition and Stampede Company. He has been a volunteer at St Margaret’s Church (Eagle Butte) and has researched and written several articles in relation to its history. Most recently he co-authored a booklet on the history of St Margaret's Church entitled “ A Tiny Prairie Cathedral”.

His  articles  can be found in his blog.

Why he is interested in Ancestry

Genealogy derives its name from the Greek words “generation” and “knowledge” and is the study of families and the tracing of their lineages and history. The results are often displayed in charts or in written narratives. The pursuit of family history and origins tends to be shaped by several motives, including the desire to carve out a place in one’s family in the larger historical picture and a sense of responsibility to preserve the past for future generations. This has always been my prime motivation. 

More importantly, I have discovered in the course of my research how genealogy and history often intersect with amazing results. As a consequence, another motivation for my writing is to draw attention to this interesting discipline and to encourage others to take up the cause of researching and documenting their own family history. 

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