With the assistance of DNA markers, genealogy tracing of a person’s ancestral past can be accomplished. This can be done by the comparison of short tandem sections of DNA strands of two or more samples. These strands are the genetic markers that prove scientifically who we are related to.
The reason these tandem pairs are used is the rarity of a mutation occurring for people that are related. In most cases, when a mutation occurs there is an addition or subtraction of just one repeating code. The rarity of this mutation occurring is 1 in every 500 generations for a single marker.
With an increase in markers that are observed comes the likely increase of a mutation being observed. When analysts observe the Y-DNA strands for comparison, 21 markers are noticed. The increase in the number of markers that are observed come the likelihood of mutation occurring. With these 21 markers, the odds of a mutation is 1 in every 24 generations.
With mtDNA, up to 65 different markers can be observed. What is known is that the more markers that are being looked for in the comparison, the accuracy of the results increase.
The greatest degree of accuracy is the closest relationship between two samples. This is the relationship between parent and child. With the advancements in modern testing techniques, the results are now 99.999% accurate.
Genealogists use this same data to determine which Haplogroup a sample is from. This is possible because of all the known results from past DNA markers. Genealogy has matured into a respected science over the years, and these results can be relied on for finding out where our ancestors came from.