Myth: A DNA test can pinpoint precisely where
your ancestors lived or which tribe they belonged to.
If your ancestors and their offspring had stayed in one geographic
region and never allowed outsiders to enter, it would be relatively
easy to distinguish their DNA (and yours) from the DNA of
people living in other regions. Over time, all of the inhabitants of
your region would come to share specific genetic mutations (usually
harmless changes in DNA), which would identify them as a
distinct population, the same way a surname identifies members
of a family.
But our ancestors didn’t stay in one place. For thousands of
years, humans have moved about, leaving their genetic imprints
wherever they procreate and making it increasingly difficult for
geneticists to distinguish one region’s population from another’s.
Scientists can make inferences about your ancestry based on
trends among populations, but they can’t say for sure that your
ancestors lived in a specific country, much less a specific town.
Testing companies analyze a person’s genetic makeup by comparing
his or her DNA to a reference database of DNA samples
from modern individuals living in various regions—such as residents
of present-day African countries. But it’s important to keep
in mind that today’s inhabitants of a given region are genetically
different from the people who lived there before migration
occurred. Just because your DNA matches the DNA of someone
who currently lives there, that doesn’t necessarily mean your
ancestors came from that place. Likewise, your DNA might
match that of a modern-day African tribe, but your ancestors may
not have identified with that particular group.
Biogeographical tests such as DNA Testing Systems’ DNA Fingerprint
tests will estimate where in the world your ancestors originated. Yet scientists haven’t agreed upon definitions for even
broad genetic ethnicities, so if you test with more than one company, you may get different results.
By combining genetic genealogy and traditional genealogical
research methods, however, you can make headway in pinpointing
your family’s origins. As more people get tested and contribute
both their DNA test results and their family trees to online
databases (see myth 5 for more on these), scientists will be able to
identify additional patterns and draw better conclusions.
This course as the first one “Genetic Genealogy For Beginners” is an expansion and goes a little more deeper into the DNA with some additional learning tools. In these lessons rather than chapter we will use Genetic Genealogy, Molecular Genealogy (the field of biology that studies the structure and function at the molecular level and thus employs methods of both molecular biology and genetics. The study of chromosomes and genes expression of an organism.) Sounds intimidating but it will be broken into manageable understandable lessons. There is a test after each lessons to help you gain a solid background before moving to Intermediate and Advance Genetic Genealogy. This will be a four week course and starts May 1 – May 26 2017.
mark you calendar for this course.
The Genetic Genealogy Standards Committee presented these standards at the Salt Lake Institute of Genealogy in Jan. 2015.
This document is intended to provide standards and best practices for the genealogical community to follow when purchasing, recommending, sharing, or writing about the results of DNA testing for ancestry.
These Standards are intentionally directed to genealogist, not to genetic genealogy testing companies. As used in the Standards the term “genealogist” includes anyone who takes a genetic genealogy test, as well as anyone who advises a client, family member, or other individual regarding genetic genealogy testing. However, it is ultimately the responsibility of those taking a genetic genealogy test (“tester”) to understand and consider these standards before ordering or agreeing to take any genetic genealogy test.
Standards for Obtaining, Using and Sharing Genetic Genealogy Test Results
There are two basic concepts that form the foundation of Genetic Genealogy. (http://www.dnaftb.org)
We humans inherit several “forms” of DNA, each of which can help genealogists research and confirm or reject different portions of a family tree. The DNA types are:
The sex-determining chromosomes, Y-DNA and X-DNA, also found in the cell nucleus.
The twenty-two autosomes and the X and Y chromsomes collectively are called nuclear DNA, as they are contained within the nucleus.
Diagram of a human cell
The cell, the basic unit of life, uses genetic material called DNA to control the vast majority of its functions. DNA (short for Deoxyribonucleic-acid) is a component of the cell that carries a set of instructions development and operation of all living things. When two or more humans share segments of DNA, there is or was a shared common ancestor that lived in the past that connect those humans. Note: For African-American’s, DNA matches may not be readily identifiable, showing the real ancestor by surname; as migration occurred; name’ changes after the Civil War, forced name changes by slave owners, post traumatic stress disorder from slavery, adoptions by families of children, lost of parents by hanging, jail and diseases from working in the fields and many other health related illnesses such as high blood pressure and cholesterol.
A very small percentage of DNA comprises genes, short segments of DNA that are used as the blueprint (map) to create a protein or an RNA (ribonucleic acid) molecule. A molecule of DNA is composed of a string of millions of smaller units called nucleotide. Together, two intertwined DNA molecules interact to form a single double-helix structure called a chromosome in the nucleus, or control center of the cell. A normal human cell has ninety-two long molecules of DNA that pair up to form forty-six double-stranded chromosomes. Each of these, in turn, forms a chromosome pair with another similar but not identical chromosome, to create twenty-three different chromosome pairs.
Double Helix courtesy of Danny Lela of the National Human Genome Research Institute access Dec. 2016
Chromosome chart courtesy of Darryl Lela of the National Human Genome Research Institute access Nov. 2016. This is called a Karyogram, which is all of the chromosomes of the human cell arranged in pairs in a numbered sequence from longer to shortest.
Note: Remember that the Mitochondria is outside of the nucleus. mtDNA and is not shown in this graphic.
The more DNA you share with someone, the more closer you are to that person.
More on this and other topics in Chapter 3
Source: http://thelegalgenealogist.com dated 22 Feb. 2017
This article was written from a Eurasian perspective. The definitions are correct.
The genetic genealogy glossary defiunition of haplogroup is “a genetic population group of people who share a common ancestor on the patrilineal or matrilineal line. Haplogroups are assigned letters of the alphabet, and refinements consist of additional number and letter combinations.”1
Okay. Great. What’s that mean?
Basically, if you think of all humans who’ve ever lived as part of the human race as a family tree, our haplogroup is what branch of the tree we can park ourselves on.
Everybody — male and female — has at least one haplogroup: our maternal haplogroup, as defined by our mitochondrial DNA (mtDNA). That’s the kind of DNA we all inherit from our mothers and that only females pass on to their children.2Our mtDNA haplogroup, then, is the branch of the tree we’re sitting on when the roots go back to the first woman from whom we descend: our mother’s mother’s mother’s mother.3
By itself, the mtDNA haplogroup tells us a great deal about our very deep ancestry many generations, even thousands of years in the past. But it also has some information we can use right now. It can tell us, for example, if our direct maternal line is of recent African or Native American origin. Or whether you, like me, have a maternal line that’s plain vanilla European.
Note that the fact that my maternal line is plain vanilla European doesn’t rule out having some more interesting ancestor from Africa or with Native American origin — it just means it isn’t my direct maternal line. It’s not in the direct line from my mother’s mother’s mother’s mother.
Only one of the major genetic genealogy companies offers mtDNA testing: Family Tree DNA. When you test at the HVR1 or HVR1+2 levels, the test looks at enough of the genetic markers to tell you what broad branch you belong to, represented by a letter like K or H. To get the specific branch — or twig! — the full mitochondrial sequence test (FMS) tests the entire mitochondria.4
Men also have another haplogroup, carried in their YDNA. That’s the kind of DNA that only males have and that’s passed from father to son largely unchanged through the generations.5 The YDNA haplogroup, then, is the branch of the tree a male is sitting on when the roots go back to the first man from whom he descends: his father’s father’s father’s father.6
By itself, the YDNA haplogroup tells the tale of deep ancestry just as the mtDNA haplogroup does, can indicate specific types of recent ethnicity — and is particularly useful genealogically to help distinguish between groups of men of the same surname: in my own research, for example, we thought our Shew line might be related to a specific Pennsylvania Shew line until we found that our line was haplogroup I and the Pennsylvania line was haplogroup R. Different branches of the human family tree entirely.
You will get a prediction of your YDNA haplogroup when you test with 23andMe and can get very specific YDNA haplogroup data from YDNA testing with Family Tree DNA, the only major genetic genealogy company that offers YDNA tests.
https://unlockinglifescode.org/media/animations/659#660 (access 2/20/2017)
If you are frustrated or just need direction sin finding all those female ancestors with missing maiden names, or if you are not sure which Julia is your great-grandmother, you can look no further than the answers provided by mitochondrial DNA (mtDNA). One of the most powerful tools available to African-American genetic genealogists and African-American genealogists (new term genetealogy (ge-neh-tee-ol-0-gee), mtDNA offers a glimpse into the the maternal lines of even your most challenging ancestors. So how can mtDNA help you?
Each mitochondrion contains its own DNA and its own protein-synthesizing machinery. They reproduce by splitting in two after they make a second copy of the DNA. In humans, the mtDNA is in the form of a circle that contains approximately 16,500 nucleotide base pairs of DNA. (DNA molecules consist of two paired strands, and each strand is a long chain of four types of nucleotides, designated A, G, C and T.) In contrast, the DNA in the nucleus is divided into 46 linear chromosomes (23 from each of our parents) that have an average length of more than 200 million base pairs. Each person’s mitochondria come from the cytoplasm of the mother’s egg. The father’s sperm cells also contain mitochondria, but they are not inherited by his offspring.
Before people started to travel around the world, the rare changes that occurred in mtDNA over time resulted in unique types of mtDNA on every continent. Therefore, most contemporary mtDNAs can be assigned to a continent of origin based on the nucleotide sequence of the most variable region (Hypervariable control region HVRI) of the mtDNA. The HVRI region is about 400 base pairs in length and is the region where the mitochondria start making a new copy of their DNA. It is the region of the DNA molecule where mutations (changes) are most likely to occur. When a scientist determines the order of the four nucleotides in this region, they find a record of all of the mutations that have occurred over time as the mtDNA was passed from mother to daughter from generation to generation. These accumulated mutations are the basis for the unique types of mtDNA found on each continent. HVR2 is the second region and they both accumulate changes relatively quickly, and thus tend to be hype-variable from one person to the next unless those people are closely related. The third portion, the coding region (CR), accumulates far fewer changes and contains the nucleotide base pair sequence for mitochondrial genes.
Example: mtDNA Family Member
|Match ID||Type||Name||Matching segments on Chromosome 2||Overlap with previous match|
|1||F2||(A982870)||104323793 – 130334843 (24.045 cM)||New Root|
Within continents, regional mtDNA variation can be observed as well. When a woman’s mtDNA contains a new mutation, her descendants are likely to live near her. Therefore, a local area where she lived will be the only place in the world where this particular type of mtDNA is found. However, whenever people moved from one place to another they took their mtDNA with them. In sub-Saharan Africa, for example, there have been extensive movements of people over time. As such, a recent study has shown that approximately half of all African mtDNAs are shared among people from multiple countries in Africa. If an African-American has one of these shared mtDNAs, it is not possible to determine which country was the original home of the maternal ancestor who came to the U.S.
A second problem is that many African-Americans have a particular type of mtDNA that is clearly African in origin, but has not yet been observed among the African mtDNAs that have been analyzed. This situation occurs because there is an incredible amount of genetic diversity among Africans and African mtDNAs have not been studied extensively. In fact, the mtDNAs from many African ethnic groups have not been analyzed at all. Additional studies will help with this situation. However, if a particular mtDNA is rare enough to be found in only a small region of Africa, there is a good chance it will be difficult for researchers to find it. Some people suggest comparing these rare mtDNAs to similar mtDNAs that have already been found in Africa. However, when these comparisons are made, the rare mtDNA is usually similar to one of the common mtDNAs that are found in many countries. Therefore, it is not likely that a particular person’s mtDNA can be assigned to a particular country of origin. This conclusion is true not only for African mtDNAs, but also mtDNAs from every other continent as well.
Y-DNA| atDNA| Y-DNA Standards
Source: Scientific America, “How Do Researchers Trace Mitochondria DNA Over Centuries?” Digital Access 12/7/2016
National Institute of Health Genome Project, Digital Library, Cell Structure 2016