A genealogical test identifies genetic markers to predict which ancient ancestral grouping your ancestors belonged. It also identifies the migration routes they took out of Africa into other parts of the world.
Genetic markers provide a comparison with others who have also taken the test, further. The higher the number of markers identified by the genealogical test, the more precise the comparison when match with other participants.
For family history purposes, it is generally best to have at least 46 markers for comparison.
Markers refer to a physical location on the chromosome.
Matching too few markers may not result in a genealogically relevant time frame. It is important to have a time frame that produces as tight a MRCA (Most Recent Common Ancestor) result as possible.
For example, 12-marker Y-chromosome tests with a perfect (12 out of 12) match results in a MRCA of 14 generations.
Furthermore, you have only a 50% probability that you can determine any shared genealogy. You can however predict your ancestral group (paternal haplogroup), and perhaps even a sub-group.
"A Y-DNA haplogroup is defined as all of the male descendants of the single person who first showed a particular SNP mutation. A SNP mutation identifies a group who share a common ancestor far back in time, since SNPs rarely mutate. Each member of a particular haplogroup has the same SNP mutation." (From the FamilyTreeDNA Website.)
Receiving a full Y-DNA 46 marker test reduces your MRCA to around 7 generations. It also decreases the likelihood of a false positive with another person.
More is not necessarily better, however. It seems that after 46 markers, you may need a genealogical test consisting of 100 markers or more to narrow significantly the MRCA range.
Autosomal DNA Test
This genealogical test is the most recent innovation for both men and women. Autosomal DNA test is great for confirming close genealogy, regardless of gender.
The current shortfall is that your matches largely depend on how your DNA compares to others in a database. Therefore, you want to use a company that has a large and growing database.
If you come from an under-represented population, it is possible you will not find matches right away. However, databases are constantly growing and you may have matches, over time. You will receive e-mail notifications about any new matches.
Paternal Lineage Test
This genealogy test analyzes specific segments of the Y-chromosome, which only males possess. The Y-chromosome passes largely unchanged from father to son. Therefore, DNA results from a male can represent the paternal lineage dozens of generations into the past.
The Paternal Lineage test also provides insights into your ancient ancestry stretching back many thousands of years. You learn about where your ancient ancestors migrated and settled as humans spread throughout the continents.
A female cannot test paternal lineage without a biological male relative. Females can recruit a brother, father, or paternally related Uncle or Cousin to provide the DNA sample.
Maternal Lineage Test
This genealogy test is available to both males and females. It traces your ancient ancestry from your Mother's side, using mitochondrial DNA.
However, the Maternal Lineage test differs from the paternal test in that it cannot validate a family relationship. If maternal DNA is an identical match with another participant it can only prove that you may have been related thousands of years ago. On the other hand, if your results differ in any way, the results prove that you are definitively not related.
Determine which of the above genealogical test is right for you. Do your genealogical test and get your information into the database.
Do not worry about privacy issues. Family Tree, Ancestry, and others have strict privacy policies. They use a tracking number, not your name, during the testing process. If you decide to participate in a group or surname project, only you will have your password.
Finally, "DNA testing conducted for genealogical purposes reveals family relatedness and currently does not provide definitive conclusions regarding a propensity toward disease or other medical conditions." Furthermore, these tests are not AABB accredited. They do not establish legal paternity or sibling relationships.
Go to this webpage about DNA testing.
An illustrated introduction to mitochondria and mitochondrial DNA
Click here for Family Tree DNA Glossary.
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