The original article appeared in”Everton’s Genealogical Helper” in November-December, 2005. A variation of this article was printed in a FamilySearch blog entitled “The “Genes” in Genealogy in 2011, The article has now been updated as of August, 2018

It’ All In the “Gene(s)alogy”

by Claire V. Brisson-Banks, BS, MLIS, AG®

From the very beginning of time, each human is ‘a likeness’ of their parents’ straight back to Adam.  Children look like their father or their mother and yet they are still unique.  How is this likeness, known as genes and traits, inherited from generation to generation of ancestors?  The genetic blueprint is “Deoxyribonucleic Acid” which is more commonly known as DNA.

Through genetic research, scientists discovered the following:

1) Females produce eggs with X chromosomes
2) Males produce sperm with an X or Y chromosome
3) How DNA is passed through these chromosomes

Common sources of DNA are hair, saliva, bones and blood.  Any of these items can be broken down into a numeric code showing certain DNA markers.  According to smarterhobby.com, there are three main kinds of genetic testing suited best for genealogists: [1]

• Y-Chromosome test
• mtDNA test
• Autosomal test

Research of human cells revealed the DNA within each cell nucleus is arranged into 46 chromosomes.  These chromosomes are broken up into 23 pairs, 22 pairs are identical as each pair contains a chromosome from the mother and the father.  The 23rd pair has either two “X” chromosomes or one “X” and one “Y” which determines a child’s sex.  So how is this great feat accomplished?

The DNA within these chromosomes, contain inherited materials from both parents.  DNA issues instructions to the proteins and to mitochondriaDNA, known as mtDNA, which also carries a very small piece of DNA.

Y-Chromosome Test:

The link through the father is the “Y” chromosome and is passed down from every father to every son!  There is a small portion passed down from father to son virtually unchanged. It is this portion of the genetic code that identifies the direct male line.

Due to the fact that the Y chromosome is passed from father to father virtually unchanged, it establishes direct paternal lines from a common ancestor and a great tool in verifying direct paternal lines as well as collaborating records and information already established through a paper trail.  There are times when mutations occur in the Y chromosome, an analysis of these mutations can be used to estimate the degree of separation between individual males in terms of the number of generations since the separation (mutation) occurred.  The individual male is known as the “Most Recent Common Ancestor” (MRCA).

mtDNA Test

A small amount of mtDNA, which are exact copies of the mother’s genetic material, is passed down to each child.  This creates the perfect genetic code to link the generations together through the mother!   It is important to remember it is only the daughters that pass it along to the next generation.  Often the maiden names of females are not included in paper records bringing about the need to verify a paper trail done through conventional research. This testing is beneficial when there is a need to establish maternal lines.

Autosomal Test

This test is the most popular DNA test in 2018 as it looks at what one inherited from all their ancestors. One can discover cousins and where their ancestors were originally located with this type of testing. Additional tools are being created to help make better use of this test each day. Special chromosome browsers have already been developed by MyHeritageDNA. Going forward, MyHeritageDNA has dedicated much of their focus on creating better digital tools to help one find their ancestral and living family members.

As a chromosome is made up of basic genetic units of repeated copies called genetic markers, individuals can be linked together into family genealogies.  This development allows any two people to trace back to a common ancestor creating a genetic pedigree.  Until this point in time, the genealogist only had written records to create their pedigree.  Following the paper trail of ones’ ancestors often leads to dead ends, due to man-made or natural disasters or just plain carelessness. There are also situations where records are not available for legal reasons due to adoptions and illegitimate children.

To compensate for these situations, we must remember we carry around in our genes the answers to these questions through DNA which can’t be lost. DNA is providing the ability to trace one’s heritage through either the male or female genes. Tracking the male line is done through a Y-chromosome test in conjunction with matching and variant surnames. Tracking the female line is done through the mtDNA.

DNA determines every aspect of human growth. Physically, DNA itself is very long, thin and extremely tightly wound bundles called chromosomes.  Taking a gene and being able to read the four chemical components of DNA, which are:

• Adenine,
• Thymine,
• Cytosine,
• Guanine

These are the key to breaking the genetic code. These 4 letters A, T, G and C make up the DNA alphabet. There are 64 possible combinations of these four chemical components called bases. After a number of processes, a single DNA strand is read and the results are a sequence from the DNA alphabet, A, C, G, T.   The DNA chain will look something like TTAACACGGTTAAC.

Using certain dyes, these chromosomes can be seen under a light microscope, creating a pattern of light and dark bands, showing differences in the amounts of A and T versus G and C. These different amounts and patterns allow us to identify the differences in each of the 23 pairs of chromosomes.  These bases are paired together, A pairs with T and C pairs with G.  Because they pair together, if one knows that an “A” is on one strand, one knows that a “T” is on the other strand.  One strand is like a negative of the other, making reading the strands easier.  One only needs to read one strand and the corresponding strand is the matching negative.  Sequencing is done through X-Ray films. The colored bases are matched to bands on the X-ray.  It is read left to right in the order of the letters. This sequence creates the “gene” in “Genealogy”.

Genealogy, paternity, migration patterns as well as how groups of people are related is traceable through the Y chromosomes.  The segments that carry genetic characteristics on the Y-chromosome are called “Markers” and each marker’s name is known as a DNA Y-Chromosome Segment Number or DYS Number.  The location of the marker on the chromosome is known as the “Locus.”  The number of repeats is called “Allele.” It is the variation of repeats of these base pairs that creates the results that allow us to verify a genealogical connection. The number of markers they search for increases the accuracy and the price of the test.

Currently there are 5 main companies one can choose from to do their testing in connection with genealogy.[2]

• AncestryDNA: Autosomal for cousin matching
• FamilyTreeDNA: YDNA & mtDNA test for the serious genealogist
• MyHeritage: Autosomal for cousin matching
• Living DNA: Best for UK roots
• 23andMe: Mostly for health screen but have genealogical screen too

When one adds their “raw test results” to GedMatch, they increase their chance of finding new relative extensively.[3] When one can find other family member, regardless of how distance, the chances of increasing one’s ancestral quest also increases substantially.

As one works on their family history, it is amazing how the number of people in one’s family begins to increase as each generation doubles the previous number of individuals.  Going back 10 generations gives us 1,024 direct ancestors.  Going back a total of 750 years gives us 30 generations and 1 billion ancestors!  Noting the plain fact of 1 billion people living at this time is impossible, tells us we are all cousins and related! Genetic research will help locate those links between each other.

Additional benefits of genetic research

• Archeological finds throughout the world
• Identify genetic diseases which could lead to possibly cures
• Forensic Science uses DNA as evidence in crimes and has assisted in many significant determinations of guilt or innocence in a court of law.

In conclusion, DNA analysis should be considered as another method in seeking our ancestors when the written word is no longer available.  Time destroys records; our genes are passed down through each generation just waiting to be identified with the correct tools.  Computers have made genealogical research easier, DNA has made the science of genealogy verifiable, the future is full of promise as new technologies emerge perhaps inventing more accurate measurements for extending one’s genealogical lines as well as locating the actual origins of ones’ ancestors.

We live in exciting times!

© 2005-2021 Timeless Genealogies

[1]Orwig, M. (2018, June 10). The 5 Best DNA Tests for Ancestry in 2018 – Which Testing Kit is Best & How to Choose. Retrieved June 11, 2018, from https://www.smarterhobby.com/genealogy/best-dna-test/

[2] Orwig, M. (2018, June 10). The 5 Best DNA Tests for Ancestry in 2018 – Which Testing Kit is Best & How to Choose. Retrieved June 11, 2018, from https://www.smarterhobby.com/genealogy/best-dna-test/

[3] (2011). Retrieved 2015, from https://www.gedmatch.com/login1.php