Can you prove a relationship purely through DNA?

[RobertCasey]

Genetic testing should be just considered another form of genealogical evidence. This evidence should be used in conjunction with other available traditional genealogical source records. I think a lot of people think that DNA technology will allow people to immediately find their lines - but their is almost always many steps involved which take time to analyze and research.

There is no doubt that some DNA tests are far superior to traditional genealogical research such as paternity tests (if done under court control as they are always done). These are way above 99.9999 % accurate and no probate record will ever approach this level of accuracy since humans are involved in creating these records (who always their own interests biasing their input). But paternity testing is an extremely limited genealogical test of father/child of living individuals.

The future of YDNA testing is extremely bright - depending on how many actually test. There are now 4,500 known YSTRs and we are approaching 1,000,000 YSNP mutations. It is estimated that every father to son will have 20 to 100 unique mutations per generation. But using all this information would really require almost everyone to test - not likely to happen as we know that not all of our cousins care about their family history that much.

The future of atDNA testing is also quite bright as well - since its very low cost and the wide net that it throws across your entire pedigree chart. Several million atDNA tests are getting be a pretty decent sample size (but most are not genealogists - it was just an impulse purchase to test medical information or geographical origins).

My parents and I have been avid genealogists - compiling nine 600 page family histories over a 30 year period - 58,000 cousins. Only a few months ago, I had a match and they challenged a marriage of two of my most elusive ancestors (surname of Hill and the person changed his first name). She sent her version where my maternal ancestor married somebody else but revealed two new ancestors for my ancestor chart - I only knew her maiden name was Reed. So with only 30 minutes of time, I sent her three death certificates of their listing her name as the mother, my ancestor as the father - different from their research. She spent 30 minutes giving me the parents of this maternal ancestor that I can document via traditional genealogy.

[IJDisney]

Hello jillruss,

These two ladies are 4-6th cousins, which mean you are looking for a link 5-7 generations ago (or even further, since this is based on probability estimates rather than hard and fast boundaries). Your hypothetical great grandmother's father is only 4 generations ago, so you may still be looking for a link 3 generations or more back. This might be a link through her non-paternal line, considering your ancestor and theirs' lived in the same area (i.e. your gt grand mother's mother).

DNA can be baffling. I'm sure you know that 7 generations back gives you 128 lines of descent (and the link could be still further back again). These two ladies could share a common Aldridge ancestor with each other (how far back is that ancestor?) but also relate to you on one or more separate lines not connected to their Aldridge common line or to each other. It could be just coincidence.

I am constructing my own DNA hypothetical tree based on DNA matches with over a dozen people in the US who all descend from different children of a common ancestor who emmigrated from the UK in the 1860s. I have no paper trail to show how I relate to them (somewhere in the estimate of two or three generations beforehand) and I'm hoping to someday find some DNA matches in the UK that match with the US lines in order to hone down the connection.

The only real way forward with your search is to find more DNA matches. Dealing with distant cousins, the more DNA matches you find who match each other and have a known common ancestor through separate lines, then the greater likelihood there is that their common ancestor is your relative.

I hope you find some answers.

[Guy Etchells]

You seem to have a predisposition against DNA, Guy. Not to mention a predisposition towards pedantry!

I too was sceptical about DNA tests before I 'gave in' and took the test, and, actually, for a while after the results came in. However, I am changing my mind the more fellow testers I contact and discover that the DNA does not lie. The latest is a lady connected (2x gt grandmothers are sisters) by the name Jones! I mean - JONES - that must be some achievement eh, even in your sceptical eyes!?

Have you considered testing yourself in an attempt to support your argument? You may be pleasantly/unpleasantly surprised.

Nothing personal intended - I believe in free speech and your right to your opinion. 

Jill

Jill I have had a deep interest and followed developments in the science of DNA since I heard that the NHGRI had sequenced human DNA back in 2003.
I also realise that although it is claimed that the human genome has been “completely sequenced I also understand that this is not accurate and there are actually gaps in the sequence which may or may not have a bearing on the results.

I also understand that DNA may be used as a tool in genealogical research as I have stated in other postings, however the question posed in this thread was -

I think I need input from Rootschatters with more experience than me of all that DNA tests entail. Can DNA matches prove something that lack of documentation can't?

The answer to that is no, DNA cannot prove something that lack of documentation can't.
It can give and indication or point the way to enable someone to draw a conclusion but it cannot prove it.
If you can be bothered to look at all of my postings on the subject of DNA you will see I have never claimed DNA lies.
If you can be bothered to look at all of my postings on the subject of DNA you will see I have stated that DNA may be used as a tool in genealogical research.
You will also see that I have stated the further back one goes with ones research there is less and less chance of a specific ancestor actually donating DNA to any particular living person. In other words the further back you go the more of your ancestors drop out of the “gene pool”.

Yes you can say I am pedantic but that is due to me studying a subject and developing a deep understanding in things that interest me to enable me to evaluate them.

Cheers
Guy

[jillruss]

Guy,  I confess to having read some of your posts on DNA - probably not all - hence my conclusion about your views on the subject.

I don't doubt for one moment that you have read more than I have on the subject and I know from other posts that you are a deep thinking person with your own opinions. I respect that - I'm quite opinionated myself!

Having said that, DNA research may be in its infancy and flawed but at the moment its all we've got over and above the conventional methods. I too was deeply sceptical but ventured to 'put a toe into the water' and am reasonably happy with the results -so far. I hope I will be able to see through any glaring errors in the same way that I would if e.g. it was blatantly obvious that a parish clerk had made an error in a parish register or, as happened with a marriage certificate for one set of my gt grandparents, their names had been transposed; or another where the names of the fathers had been transposed. You get my point - nothing is perfect (nor probably ever will be), but we still use these tools in our genealogical research because they're there and because we can.

I hope one day you give it a whirl!!

Best,
Jill

[Guy Etchells]

Thanks Jill

[Jill Eaton]

Many new technologies are viewed with suspicion and are often viewed as inferior to "the old ways" but rapidly become acceptable.

Then there comes a point where we can't imagine how people actually managed without!