DNA Testing - Why Not

[Shropshire Lass]

I, too, have done it - well, got Dad to have his done - to try to break through an illegitimacy brick wall.  Nothing has come from it yet but, as more people have the tests done, we may get a result.

[scooper200]

Helen: I won't reply to your post directly but I'll refer you to books by Bryan Sykes that should answer the question as to the value of DNA testing.

[polly88]

I would love to have it done and have been thinking of it for the past year.  I have posted before on my indecision.  The reason(s) I haven't done it yet is mainly cost.  But also when researching the various DNA tests, and the name I am most interested in (Begley), I find hardly any Begleys have done it, and they are mostly in US.  I'd be worried I'd have the same lack of response as msallen.  I haven't given up the idea though.  ps Ruskie you made me laugh!

[corinne]

I wouldn't be bothering just for myself, but at some point I will be initiating a DNA study as part of a one name study.  I think that is really where the huge benefits can come in.  I think I'd encourage anyone interested in the whole DNA thing to see if there is a surname society for their name, or a one-name study, and see what they are doing first.  The benefits there are that you can make a lot more headway in linking larger groups of people together, or proving some of those connections from quite some generations back that you had to just guess at before. 

I really don't see the benefits of just getting tested as an individual and finding someone else with a common ancestor 6 generations back, if you are just researching your own immediate family.  If you are looking at cost as well, most of the surname societies or one-name studies can get test kits cheaper one way or another - either by funding them from donations from members of the group or buying in bulk, so thats another reason to go with an already recognised study group. 

Having said all that, are there any male Sennett's out there (from any line) who would be interested in getting their DNA recorded?  As the administrator of the Sennett one-name study, I have a hunch that DNA testing will find that several of the (at the moment) separate lines of Sennetts in the UK will end up having the same common ancestor in Ireland.   

[Redroger]

Helen: I won't reply to your post directly but I'll refer you to books by Bryan Sykes that should answer the question as to the value of DNA testing.

They are well worth reading, as is "The origin of the British" by Stephen Oppenheimer, lengthy though.

[nickgc]

Polly88,

The benefit of the newer autosomal DNA testing is that it doesn't just test your surname line.  That is only done by a Y DNA test, and can only be done by males.  Look at this chart:

http://en.wikipedia.org/wiki/File:CousinTree.svg

All of these people share a significant portion of your DNA.  Note that some of them may well have been born Begleys, such as a daughter of your grt gpa B's brother who later married.  Her descendants would be closely related to you and not share your name.  Names mean nothing in this context unless you are only interested (as in a one name study) of pursuing a very narrow part of your genealogy.

You obtain ~50% of your DNA from each parent; 25% from each grandparent; 12.5% from each great grandparent, and so forth.  Consequently that means you share ~12.5% with 1st cousins, 6.25% with 2nd cousins, 3.125% with 3rd cousins, >1.5% with 4th cousins.  This is what makes these tests worthwhile:  they can give you pretty darn good results, with a high degree of certainty, back to 5th cousins (descendants of your 4x grands).

I'm not really trying to convince anyone to do DNA testing, although I would like to see the base of those tested expand greatly.   I am interested in seeing why people don't want to do it. 

I rather facetiously put the choice of "fear of cloning" into the poll because I have seen people on this site imply that they had fears like that in the past 3 years.  Happy to see no one has chosen it so far!

Nick

[nickgc]

I mispoke in some of the percentages above, so here is a picture that shows the percentages of DNA a relative is likely to share with you.  No wonder they say a picture is worth a thousand words...

[Ruskie]

That there:

You obtain ~50% of your DNA from each parent; 25% from each grandparent; 12.5% from each great grandparent, and so forth.  Consequently that means you share ~12.5% with 1st cousins, 6.25% with 2nd cousins, 3.125% with 3rd cousins, >1.5% with 4th cousins.  This is what makes these tests worthwhile:  they can give you pretty darn good results, with a high degree of certainty, back to 5th cousins (descendants of your 4x grands).

and that diagram there:

Here is a better picture that shows the percentages of DNA a relative is likely to share with you.

That is confusing and puts me off. I cannot get my head around it (though I think I may be a bit numerically dyslexic  ).

You are also surveying people here who are interested in genealogy and DNA testing can be part of that, but I think the broader population really don't care. Did I dream that there was talk of DNA testing all newborns? If so, eventually someone may find some use for the information though it could be classed as invasion of privacy etc etc.

I agree with corinne's comments re the usefulness of the test, but if it was free you'd get a lot more takers... 

[nickgc]

Hi Ruskie,

Right you are on the free bit:  1 1/2 years ago (or maybe it was on DNA Day this year, 23andMe had a one day free test with a $5/month subscription for a year.  I kick myself for missing it.  I probably spend more than that on gasoline driving to the library a few times a month... and its pretty close.

People in the know hint that they will be able to do a "whole genome test" for under $500 in 4-5 years.  Currently it is very expensive ($10K?).  But since I became a grandfather a couple of years ago, I didn't want to wait that long.  A cheap full genome test will be a huge boost for medical science, but will also have wide impacts on genetic genealogy.

If you have specific questions about how the numbers work, send me a PM and I will try to respond.

Nick