Thursday, November 16, 2006

DNA testing for recent (but deceased) ancestors

from Google Groups: soc.genealogy.britain:-


I've been following the recent thread on DNA testing with interest. I wonder if I could ask a specific question.

I am unsure who my grandfather was. My late father's birth certificate gives no name for his father and he never really discussed his father apart from saying that he died when he was young. Based on stories from relatives I now have two prime suspects, my paternal grandmother's first husband (candidate
1) and her sister's husband (candidate 2).

All of these individuals are now dead along with their children. I am however in contact with grandchildren of my paternal grandmother and her first husband (candidate 1) and with grandchildren of my grandmother's
sister and her husband (candidate 2).

Is it possible that DNA testing of samples from myself and my cousins could
establish which of the two candidates is most likely to be my paternal grandfather?

If so how would I go about doing this - are there companies
which offer this service?

and an answer from another blogger of the eboracensis family history and genealogy blog:-

Hi list.

I'm new to this list having subscribed because I browsed through the archives and thought that the content looked good.

I thought that I'd just add a little bit to the recently discussed thread on DNA testing - my day job is actually as a geneticist. I specialise in how DNA gets inherited differentially from mothers or fathers. This is probably why I'm into genealogy as well.

Anyway, I read Roy's earlier post, and tend to agree broadly with his points. DNA is one small piece of evidence, it really isn't going to help individual genealogists studying their own family history that much.

The main point here is that you have to know what question you wish DNA testing to answer. It's main uses for individuals (as I can see) are to:

1) establish paternity/maternity or perhaps even grand-paternity/grand-maternity where there are some confusions over this issue.
2) for people who know they are of mixed origins to suggest some distant ancestors, e.g. whether you may have native American ancestors - this really doesn't tell you very much though, other than you are x% likely to have ancestors who were from this or that 'ethnicity'.

The other usage for DNA techniques that is often cited is that people researching the same surname could evaluate whether they are from the same paternal ancestor - or in DNA terms, from the same 'progenitor Y chromosome'. ie if I'm researching the name CURLEY in Birmingham (which I am), I could test to see whether my Y chromosome is identical to some other CURLEY in Boston, Mass, for instance, and that may suggest whether we came from the same male CURLEY in Ireland before the potato famine.

If there is a match here, than that would suggest that i'm very very likely to be related at some point in recent history (though how many generations back is harder to know). However, if the Y chromosome does not match does this suggest to us that we are not related? Well, it probably means that we are not related to that same male ancestor. It does not mean that we were not related to that male ancestor's wife. For instance, it may just mean that at some point in the past that two CURLEY sons who were thought to have the same father and therefore got the same surname, may not have had the same father. Believe me that it is not that uncommon to observe this phenomenon in genetic studies.

Moreover, I also think this is where DNA research and family history differ somewhat. Even if the father stated in the baptismal entry or birth certificate of a particular male ancestor is not exact, should this mean we shouldn't follow his line backwards? Well, for most lines we presume that the father is the father and follow it back anyway, which I think is good - we are who we are as much (actually more) because of who brought us up as who are biological parents (who gave us our DNA) are.

In summary, think it has some uses, but these are in a few instances only. And, it is much better for individual family historians who are interested in researching their ancestors to use the traditional methods.

Hopefully, I have made some sort of sense here?



Dr James Curley
Post-doctoral fellow in behavioural biology, supported by the Leverhulme Trust.
Charles & Katherine Darwin Research Fellow, Darwin College.

University of Cambridge: Department of Zoology -- Sub Dept of Animal Behaviour


Post a Comment

<< Home