|Should we say that genetic is at the
service of genealogy, or that genealogy is at the service of genetic...?
In fact, it's a little of both. Although the science known as genetic genealogy is fairly new to the genealogist, genetics itself has been around for quite a while already. And needless to say, that it will eventually become a great tool, particularly when facing a difficult genealogy research due to missing documentation, as is often the case in Acadia and other regions of America, for various reasons such as floods, fires, vandalisms, or whatever else may have happened thru the centuries. But you may wonder how genetic genealogy can be of any help to you; surely, it cannot replace missing vital records, but as you'll see, it can serve as an additional tip to lead your research in the right direction...
Genetic study based on DNA results
What is DNA ? In short, DNA (deoxyribonucleic acid) is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms. DNA molecules contain hereditary (genetic) information, unique to each individual. The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in regulating the use of this genetic information. Along with RNA and proteins, DNA is one of the three major macromolecules that are essential for all known forms of life. (source:https://en.wikipedia.org/wiki/DNA).
DNA testing, also known as fingerprinting or profiling, is a technique employed by forensic scientists to assist in the identification of individuals by their respective DNA profiles. DNA profiles are encrypted sets of numbers that reflect a person's DNA makeup, which can also be used as the person's identifier. DNA testing is based on the following theory: all cells in the human body, except red blood cells, contain DNA; the structure of the DNA of a person is identical throughout a person's body; the DNA structure is constant from a person's infancy through their death; and finally that no two people, except identical twins, have the same DNA. It can be extracted from blood, skin tissue, sperm, saliva, mouth scraping, bones and hair.
Genetic genealogy is the application of genetics to traditional genealogy. It involves the use of genealogical DNA testing to determine the level of genetic relationship between individuals. The two most common types of genetic genealogy tests are Y-DNA or Y chromosome (paternal line) and mtDNA (maternal line). These tests involve the comparison of certain sequences of the DNA of pairs of individuals in order to estimate the probability that they share a common ancestor in a genealogical time frame, and to estimate the number of generations separating the two individuals from their most recent common ancestor (or "mrca")
There is a third type of genealogical DNA testing, known as Autosomal DNA testing, used for determining biogeographical and ethnic origin, but these tests have less relevance for traditional genealogy. Nonetheless, they are becoming popular among those who are researching their ethnic origin, particularly when genealogy results differ from the oral traditions which have been transmitted by their elders, often for many generations. Autosomal testing attemps to measure an individual's mixed geographic heritage by identifying particular markers, called ancestry informative markers or AIM, that are associated with populations of specific geographical areas. It's purpose is to determine the genetic percentages of a person's ancestry from particular continents or regions, or to identify the countries and tribes of origin on an overall basis. Although their validity and reliability have been called into question, they continue to be popular.
Paternal and maternal DNA lineage
The yDNA or Y chromosome is transmitted from father to son exclusively, and genealogically speaking, corresponds to a patrilinear genealogy line, starting with a male descendant such as yourself, going from you to your father, than to your father's father (your grandfather), and so on, untill you reach your last known male ancestor in a direct line.
mtDNA on the other hand, is transmitted from the mother to all her children; although both males and females receive it at birth, only females can transmit that gene to their offsprings. To identify the ancestor represented by an mtDNA result, you simply have to do a matrilinear genealogy line, starting with yourself (male or female), going to your mother, than to her mother (your grandmother), and so on, untill your reach your last known female ancestor on your mother's side. Although the mtDNA results will not identify an individual with 100% accuracy, due to insufficient information collected through various populations over the years, but it will permit you to exclude a possible hypothesis.
Both mtDNA and Y chromosomes or Y-DNA are grouped into lineages and haplogroups; these are often presented as tree-like diagrams.
The following simplified graphic should help you to understand the principle of transmission of the Y chromosome (yDNA) and the mtDNA.
Genetic genealogy gives genealogists a means to check or supplement their genealogy results with information obtained via DNA testing. A positive match with another individual may provide information on ancestral homeland, and locations for further genealogical research, as well as validate existing research, or even confirm or deny suspected connections between families and theories regarding ancestry.
However way you chose to use genetic genealogy, there is one thing that you cannot get away from: you still need to complete and properly document your genealogy research in order to properly understand and apply those DNA results for the purpose they were intended for.
If genetics and genealogy go hand in hand, and if they are going to be of service to one another, it is therefore imperative that they be of service to you, the genealogist. And for that to happen, you have to do an impeccable and documented research, otherwise, it won't mean squat...!
When genealogy and DNA collide...
yDNA or mtDNA results can be very useful to the genealogist, particularly when documentation is missing in a genealogy research. But the subject of DNA combined with genealogy remains a sore subject as it is a thorn in the backside of many genealogists and historians. A subject of controversy in many cases, it is nonetheless quite interesting to compare the DNA results of certain individuals versus their genealogy results.
A detailed study published in 2007, of the mtDNA results of Catherine Pillard, a well known King's daughter in the history of Nouvelle-France, and the subsequent articles regarding the genealogies of four of her descendants, created such a controversy. Originally classified as being of Algonquian-Siberian origin, Haplogroup A*, it did not sit well with many genealogists and historians, who still cannot come to a consensus on that subject. And more recently, due to the insistance of a DNA expert who didn't much care for Catherine's Native status, her DNA results were re-classified as A10, of Siberian origin from the Oural region ! Needless to say that historians, genealogists and genetics experts are not all in agreement with that new conclusion...! That's what is known as evolution. Things keep changing, and it's safe to say that the story will not end there...
A similar case if now being studied, and it is bound to create quite a controversy. It involves the descendants of Germain Doucet, Sieur de LaVerdure, one of the pioneers of Acadia. It appears that the yDNA results of eleven descendants of two different sons of Germain Doucet are not a perfect match. There's more to come, so stay tune...
© All rights reserved 2007-2011 - GenInfo.org