HOW WE COMPARE
Y-DNA markers are expressed in numbers called alleles. The more mismatched markers, the greater distance from The Most Recent Common Ancestor (MRCA)
In the following section, "HOW WE COMPARE," family groups and subgroups are delineated by the white bar. Differences in DYS values within family groups are emphasized in bold italic script. The faster moving alleles are written in red.
The Y-Chromosome Haplogroups are accentuated by the gray background.
*It is obvious from our observation of 1000's of
samples that some markers change or mutate at a faster rate than others.
While that actual 'faster rate' has not yet been definitively calculated,
not all markers should be treated the same for evaluation purposes.
The markers in red have shown a faster mutation rate then the average, and
therefore these markers are very helpful at splitting lineages into sub
sets, or branches, within your family tree.
Explained another way, if you match exactly on all of the markers except for
one or a few of the markers we have determined mutate more quickly, then
despite the mutation this mismatch only slightly decreases the probability
of two people in your surname group who match 11/12 or even 23/25 of not
sharing a recent common ancestor."
(Family Tree DNA)
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WHY THE Y?
Each individual inherits 48 pairs of chromosomes from his/her parents: half of each pair from the mother and the other half from the father. Only one set of chromosomes does not combine with the chromosomes from the other parent: the X chromosome and the Y chromosome. An individual is a female if she inherits an X chromosome from each parent (XX). He is a male if he inherits an X from the mother and a Y from the father (XY).
Because the Y chromosome is passed down directly from father to son, because it changes slowly and predictably over hundreds of years, and because each Y chromosome has a distinctive "signature," Y-DNA testing can be used to determine from which paternal line an individual has descended. From the present Y-DNA testing results listed below, we have identified seven distinct family groups. One of these groups has a subsets, or "branches." Groups probably have a common ancestor in the recent past, while the subsets have a probable common ancestor within hundreds of years.
For example, two of the individuals from the Henry b. England 1705 are first cousins (6776 and 5783.) They match exactly, as we would expect. Two of the individuals from the Thomas b. Va. 1720 group (5870 and 5890) are father and son. They also match exactly, as we would expect. HOWEVER, the Henry descendents and the Thomas descendents don't match. We know that we need not waste time looking for a common ancestor for all four individuals. There is none. This new knowledge helps us " cut to the quick" and focus our genealogical research in the right direction.
Some of us have been surprised by the relationships we have discovered. This is the fun of the project.
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