Statistics Used in Genetic Genealogy
The MRCA and MLE calculations rely heavily on the mutation rate of the loci. Previously, the Y chromosome mutation rates that have been used for genealogical purposes have ranged from 0.002-0.004, depending upon the testing laboratory. This value is known as the mutation constant and may be represented by the term µ (pronounced my
). This value is the rate at which a change (mutation) is identified at a particular locus from a father to a son. Each marker tested on the Y chromosome has its own mutation rate, these mutation rates are known for many of the Y chromosome loci across several human populations (publication is in press). The mutation rate can be affected by several different factors such as population, haplogroup within a population, length of the allele, region on the Y chromosome, and size of the repeat structure. For those loci where the mutation rate has not yet been determined, Relative Genetics has chosen to use a rate of .0028. As more data on Y chromosome mutation rates becomes available, we will re-evaluate our statistical calculation to reflect a more precise measurement for each locus.
To compare the MRCA and MLE values of the 18, 26, and 43 marker tests, go to the next page.
For more information on MRCA, MLE, and understanding comparisons between individuals, refer to the next 2 sections of the tutorial.
