DNA testing - genetic genealogy

[DevonCruwys]

It's like a matchmaking game. A father and son would normally match on 37/37 markers. Two first cousins or second cousins with the same surname would match on 37/37 or perhaps 36/37. As you go back in time more mutations creep in so two sixth or seventh cousins might match on 34 or 35/37 markers. When you take a Y-DNA test your results go into the database and you are given a list of all your close matches (ie, 34/37, 35/37, 36/37). Your matches are those people with whom you share a common ancestor on the direct paternal line so if there was a surname change with an illegitimacy the match would still be picked up. The problem with a DNA test is that it only tells you that you share a common ancestor but doesn't tell you in which generation you share that ancestor. The range of possibilities is very wide. I have two eleventh cousins who match on 35/37 markers and two second cousins who match on 35/37 markers. Some of the matches you pick up will be from 600 years ago or more where for most people there will be little hope of finding a paper trail connection and especially so if there has been a surname change. By adding extra markers you increase the resolution of the test, which is especially helpful when seeking matches with other surnames. These guidelines help to explain how the matches work:

http://www.familytreedna.com/genetic-distance-markers.aspx?testtype=37

http://www.familytreedna.com/genetic-distance-markers.aspx?testtype=67

It is possible to order a 37-marker test and upgrade later. If you belong to a rare haplogroup then it might not be necessary as you will get fewer matches anyway, but you won't know this until you test. It all makes much more sense when you test yourself and have your own results to look at!

Debbie

[acorngen]

Debbie,

But there in lies my problem.  If my son had been conceived from an illicit affair he would have no matches with anyone within my direct line.  Yet the was you make your point and the links that are shown suggest that he would.  Now what isnt clear is whether this DB you talk about keeps all surnames and their profiles and if so they can then obviously match to a known group.  All this is doing is presenting a DNA company with a large amount of money and a FH with the headache of working out how they connect.  With illigitimacy there is no way they could find that information so in reality it is a waste of time within the genealogical field.

It is about as much use as those who have the same haplo group as the UK royal family.  They then want to try and prove descsent but dont realise that the particular Haplo involved with the same mutations is prevalent all across Europe.

[DevonCruwys]

If your son was born from an illicit affair he would not have the same Y-chromosome as you and you would both only match on a few markers and might even be in a different haplogroup altogether. Family Tree DNA now has almost 200,000 Y-DNA results in its database. Both of you might still get matches within the database at 37 markers. However, even if the surname of the real father was not known, if he has close matches at high resolution with other surnames this would provide clues about the potential surname of the biological father. You would still have to do the paper research to work out the actual connection.

Some adoptees have been able to trace their birth fathers through DNA testing. Dick Hill's website has some useful information:

http://www.dna-testing-adviser.com

The success rate is currently about 30% but I think it would be lower for people in the UK.

There have even been cases of sperm donors finding the identity of their fathers through DNA testing:

http://news.bbc.co.uk/1/hi/health/4400778.stm

With illegitimacy, adoption, etc, it is all a matter of luck as to who else is in the database and whether or not they have the information which might help.

Most people however use DNA testing within structured surname projects which are aiming to test all lines and work out which lines are genetically related.

[NJK]

Here is a link to another interesting story about a man who confirmed through DNA testing that his grandfather, who had always gone by the surname Brown, was actually a Baumgardner:

http://randymajors.com/2010/12/man-who-wasnt-john-charles-brown.html

This story is an excellent example of how Y-DNA testing can help confirm a surname change.

Nancy

[DevonCruwys]

I've just remembered there is also an excellent example in the Swinfield DNA project where the real father turned out to be the lodger who was present in all the censuses!

http://www.familytreedna.com/public/Swinfield/default.aspx?section=results

Debbie

[Ceeoh]

I have reached a point where the only possible way  I can confirm whether my paternal progenitor is correct is to ask a distant male relative (1st cousin once removed), and a descendant from a brother in the same line if they would be prepared to take the DNA 37 marker test.

Both gentlemen live in the U.K. and I would possibly have to offer financial assistance as this would be for my benefit (but also of interest to them).   Could someone please advise where and what costs I am looking at?

Ceeoh

[nickgc]

Ceeoh,

Look at ftdna.com under "products".  Current price is $169US.  If you are able to link to a family project you can save about $20.  If you had asked about 6-8 weeks ago you could have had each done for about $119 with end of year sale and family project discount.  FTDNA is the largest, usually cheapest, and probably most respected company for genealogical DNA testing.

Nick

[Ceeoh]

Oooerrrr ! what would that be in Pounds to be coverted to Rand our rate of exchange at the moment is we pay R11.68 for GBP1  i.e. GBP60 would cost me R664   Don't know the Dollar/Rand exchange rate.

[youngtug]

http://www.xe.com/ucc/convert.cgi?Amount=1&From=ZAR&To=USD&image.x=45&image.y=6&image=Submit