DNA Types Used for Genetic Genealogy

DNA encodes the complete Genetic blueprint of human beings. It's what makes the billions of people on the planet unique, yet at the same time, genetically similar to their parents and ancestors. DNA is found in most cells in the human body, and can be classified into three DNNA types that are useful in genealogy:

Y-chromosome DNA (Y-DNA)
Mitochondrial DNA (mtDNA)
Autosomal DNA (atDNA)


Y Chromosomal DNA (Y-DNA) is only carried by males, who inherit it from their fathers. Y-DNA is found in the nucleus of all male human cells and carries information which is found in the Y chromosome. One of two gender determining chromosomes, the Y chromosome is passed along from male to male via a sperm cell which contained the Y chromosome of the father. The sperm cell having a Y chromosome determines that the child will be male thus only males have the Y chromosome and only males can pass along the Y chromosome from father to sons. Y-DNA STR markers are what are used in typical surname projects.

Y-DNA is particularly useful for tracing one's direct paternal line (father, paternal grandfather, etc.) because it changes slowly from generation to generation, and in most societies, the surname of the father is also inherited by his sons. Women, on the other hand, do not have Y-DNA. They neither inherit it from their fathers nor pass it down to their sons. In other words, a grandson does not inherit Y-DNA from his mother's father. Women may still benefit from Y-DNA in their paternal line research when the DNA results of their father or brothers are compared with those of other males.


Mitochondrial DNA (mtDNA) is carried by both males and females, but is only inherited from the mother. This non-nuclear DNA is contained in the Mitochondrial organelles which are located inside the cells but outside of the cell nucleus in all of a mother’s children, both male and female. We get our mtDNA only via the egg cell of our mother, therefore only females can pass on mtDNA to their offspring. This makes mtDNA useful for tracing one's direct maternal line (mother, maternal grandmother, maternal great-grandmother, etc).


Autosomal DNA (atDNA) is carried by both males and females. atDNA is found in the nucleus of all human cells and carries information which makes up our individual genetic identity which is the random combination of genetic information passed down to us from all our blood-line ancestors consisting of the merged set of chromomsomes found in the nucleus of cells. These are the chromosomes that determine our unique identity and appearance.

We get this randomly assorted merged set of chromosomes ( Admixture ) from our mother and father. For females there is an admixture of two X chromosomes and for males an X from the mother and a Y from the father. For males there is no mixture of the X and Y, they are inherited as complete chromosomes, one from each parent. There are 44 autosomal chromosomes arranged in 22 pairs numbered 1-22 from the largest set to the smallest set. These are passed down to us from our parents and the mix is random. atDNA. STR markers are what are used for the typical paternity tests and individual identity tests in forensic tests and are recently being used in genealogical testing.

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