Genealogy Search Tips

Use DNA Testing to Determine Your Ancestry

The 3 Ancestry DNA Tests

Genetic Genealogy is the use of DNA testing in conjunction with traditional genealogy search to estimate and document the relationships among individuals.

For example DNA tests might indicate that 2 individuals are 2nd cousins. And obituaries, death certificates and other documents might indicate that the grandfathers of the 2 individuals were brothers. So in this case DNA testing and traditional genealogy search would confirm each other.

There are currently three Ancestry DNA or Genealogy DNA tests used in genealogy search.

These 3 tests are the Autosomal DNA Ancestry Test, the Y Chromosome (Y-DNA) Ancestry Test and the Mitochondrial DNA (mtDNA) Ancestry Test.

Scientific Basis for the 3 Ancestry DNA Tests

DNA from a mother and father is passed to their child unchanged. So the DNA inherited by a child is a copy of DNA from his or her parents.

However sometimes there are mistakes or mutations in small sections of the DNA and so some portion of the DNA is passed from parent to child with changes or mutations.

When an individual who has received a DNA mutation has a child he or she will pass on that DNA mutation to his or her child.

So DNA mutations can be considered new branches on a Family DNA Tree. By determining when and where these mutations occurred genealogists can discover information about the ancestry and relationships of many of the individuals in a Family.

And additional ancestors and relatives can also be found when certain DNA segments are shared by individuals.

Autosomal DNA Ancestry Test

Autosomal DNA refers to the DNA in the "autosome" chromosomes, the non-sex chromosomes, which are inherited from both parents. So the Autosomal DNA Test traces the ancestry of both the mother and father.

Humans have 2 copies of 23 chromosomes (1 from the mother and 1 from the father) and one chromosome determines a person's sex - 2 Xs for female and 1 X and 1 Y for male. The other 22 are the autosome chromsomes.

The DNA in these autosome chromosomes is passed unchanged from both mother and father to the child and so the autosome DNA inherited by a child is a copy of autosome DNA from his or her parents.

But mutations can occur at various locations in any of the 22 autosome chromosomes received from both parents. And these mutations can provide information about the relationships among individuals on a family tree.

To learn more about Autosomal DNA testing visit

Y Chromosome (Y-DNA) Ancestry Test

The Y Chromosome is a sex chromosome and those with this chromosome are male. So the Y-DNA Test traces the male ancestry in families.

The DNA of a male's Y chromosome (Y-DNA) should be exactly the same as his father's, paternal grandfather's and the other males in this line for thousands of years – because a man passes a copy of his Y chromosome unchanged to all of his sons.

However from scientific studies we know that sometimes a part or parts of the DNA will randomly mutate or change. If a son receives his father's Y-DNA with a small mutation or change then the son will pass on that mutated or changed Y-DNA to his sons who will pass on that mutated or changed Y-DNA to their sons.

These mutations or changes in the Y-DNA are used to determine the relationships among individuals and create a family tree because each mutation or change is like a branch on a tree that is slightly different from its parent.

To learn more about Y-DNA testing visit

Mitochondrial DNA (mtDNA) Ancestry Test

Mitrochondrial DNA refers to the DNA of the mitrochondria which are organelles in a woman's egg. So the mtDNA Test traces the female ancestry in families.

Both sons and daughters receive the mitochondrial DNA (mtDNA) unchanged from their mother but only the daughters can pass the mtDNA on to the next generation.

A woman's mtDNA should be exactly the same as her mother's, maternal grandmother's and the other females in this line for thousands of years.

However from scientific studies we know that sometimes a part or parts of the DNA will randomly mutate or change. If a daughter receives her mother's mtDNA with a small mutation or change then the daughter will pass on that mutated or changed mtDNA to her daughters who will pass on that mutated or changed mtDNA to their daughters.

These mutations or changes in the mtDNA are used to determine the relationships among individuals and create a family tree because each mutation or change is like a branch on a tree that is slightly different from its parent.

To learn more about mtDNA testing visit







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