Dear all,
There seems to be some loose terminology and shaky science being put around
here, so if it isn't too presumptuous of me, I hope this helps.
The Y-chromosome research is about tracing genetic ancestry in the male
line. That is, if you are male, your descent from your father's father's
father's father's..... Women neither pass on nor receive a Y-chromosome,
they just don't have them (barring chromosomal abnormality, which does
happen but I think usually leads to infertility so we probably don't have to
worry about it).
*If* your surname did the "conventional" thing and passed from genetic
father to son at every stage, then your Y-chromosome ancestor will have your
surname. That is the basic thing that all these surname Y-chromosome
studies are about. If at any stage the surname was passed by the mother, or
if the surname was passed by a man who was not the genetic father, or if the
surname was adopted or for any other reason doesn't match the genetic
father, then the Y-chromosome will not match the surname.
It *doesn't* necessarily mean that you are not descended from the person in
question who shares your surname, especially in the case that the surname
was passed in the female line in at least one generation.
As one of the linked websites pointed out, a Y-chromosome match doesn't
prove descent from a specific individual, but it does make it extremely
likely that you and that individual share the same male-line family tree.
You may be ancestor and descendant in the male line, or you may be cousins
at some remove, again in the male line. It is very unlikely to be pure
coincidence, especially not if there is some other evidence linking you,
such as conventional genealogy.
The mitochondrial (correct spelling) DNA thing is more or less the same, but
related to the female line, ie to your mother's mother's mother's
mother's.... Everyone has mitochondrial DNA, so you can perform the
analysis on men, but only the mother passes it to the child so, like
Y-chromosome DNA, it goes down the generations without being mixed with
genes from the other parent.
Because it doesn't match surnames in a patrilineal society like ours,
there's less interest in this kind of analysis, and it is harder to recruit
a sample of people to study a tree, like you can with a rare surname in the
male line.
So in every generation, you have one ancestor, the one in the male line, who
gave you your Y-chromosome, and you have one ancestor, the one in the female
line, who gave you your mitochondrial DNA. All the other ancestors, the
ones in the mixed male-female lines, gave you only ordinary DNA which isn't
subject to this kind of analysis. But they are still your ancestors, so
don't believe sweeping statements like I have read today about a failure to
find a match iin these studies proving that you are not descended from
someone at all. They can support or disprove a specific link, but only in
one of the single-sex lines.
Good luck with your studies, Barry and friends.
I'm not connected, so if there are still any list members who have
connections with any other Carruthers genealogy, don't forget to be posting
it. There are other branches and probably other origins of the surname!
Ian.
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