Can DNA solve illegitimate ancestry?

[paulanthony262003]

Dear All,
Apologies if this has been asked before, but I was wondering if a dna test could help me break down that big brick wall that we have all encountered at some point  in our trees, an illegitimate ancestor, or in my case two illegitimate ancestors in the same generation?

On my paternal line, my great grandfather and his future wife were both brought up in care and so neither of them ever knew who their birth parents were.   I am hoping that a DNA test on myself would help to establish a bloodline for my great grandfather, and that a DNA test on a certain female descendant would be able to establish a bloodline for his future wife, my great grandmother.

How helpful could a DNA test be to me for this set of particular circumstances and which company or particular test ought to be the most appropriate for helping me to discover where they came from, etc?

Hoping someone can offer some guidance on this complex issue for me.
Regards, Paul

[Redroger]

It certainly helped me break down a brick wall for a relative who I had no idea existed. If you send me a personal message I will happily provide details, but as he is living it would be inappropriate to do so on the open pages.

[andarah]

My husband's g grandfather, in his paternal line, was illegitimate.  We did a DNA test to try to establish a surname. In the results, I have about 30 surnames, and none have more than 3 people. I have 4 completely different surnames, all with 3 people. I am probably slightly further ahead, but not really.

[DevonCruwys]

Paul

If the paternal great grandfather is on your direct paternal line (ie has the same surname as you) then you can take a Y-chromosome DNA test to see if you have any matches with other surnames which will provide clues to his origins. The only company I would recommend for this type of testing is Family Tree DNA. They have the largest and most international database with getting on for half a million Y-DNA results. You should start with a 37-marker test or preferably a 67-marker test. They currently have a sale on until 26th July. Much depends on who else is in the database. Some people get matches immediately, others have to wait. But once you've tested your results stay in the database, you continue to get notified of matches and you don't have to pay any further money.

The female ancestor is more difficult. You could try getting a mitochondrial DNA test done on a direct female-line descendant. See this chart for the path of mtDNA inheritance:

http://www.isogg.org/mtdnapath.htm

You would need a full mitochondrial sequence test from FTDNA for genealogical matches but not so many people have tested at this level so the chances of getting a breakthrough are lower. It's also much more difficult researching the female line.

An autosomal test could help in the long run (either 23andMe or the FTDNA Family Finder test) but it all depends on who matches you and how much research they've done. This test gives you matches on all your family lines so you have to do a considerable amount of work to establish who matches you on which particular line. You might like to read some of the articles here or watch the video to understand how the tests work:

http://www.isogg.org/wiki/Autosomal_DNA

Both mtDNA and autosomal DNA would probably be long-term investments and I would recommend starting with a Y-DNA test.

 

[paulanthony262003]

Thank you for this help and advice. 
I will now go ahead and try a 67marker Y-DNA test to begin with, as suggested by 'DevonCruwys' and while there is still a sale on. However, I will try the mitochondrial or autosomal tests at a later date.
Thank you all again, it has been a great help.