Should I expect a match with Family Finder?

[Leta]

I had a male direct line cousin take a Ydna test. He matches other Ydna results with my maternal surname.

I of course do not match since I am female, so I contacted one of his Ydna matches (2 generation spread) who had also taken a Family Finder test, was able to obtain their GEDmatch kit number for the FF data, and compared my personal GEDmatch kit with theirs. The result was "No DNA match".

I have had reason to suspect there may have been a deviation in the line at either my mother or her father's birth. My question is, how definitive is this result? Essentially I am not a match for a close match to my 2nd cousin. Would this be common?

Thanks for your input.

[John McCoy]

If you and the other persons are indeed second cousins to each other, it would be very unusual not to match using the default criteria on GEDmatch.

It was not clear from your post whether you have actually verified by traditional genealogy that the two people you compared should be second cousins -- that is, that they are both believed to be great-grandchildren of the same couple. If the paper trail says they are more distantly related, the odds of NOT matching increase substantially. The current rule of thumb says about 10 percent of 3rd cousins and about 50 percent of 4th cousins will not match by the default criteria.

[ech124]

https://isogg.org/wiki/Cousin_statistics

The post does not specify how many SNPs are used in your Gedmatch comparison. Comparing different companies and different chip versions could also impact the statistics.

[MMaddi]

I had a male direct line cousin take a Ydna test. He matches other Ydna results with my maternal surname.

I of course do not match since I am female, so I contacted one of his Ydna matches (2 generation spread) who had also taken a Family Finder test, was able to obtain their GEDmatch kit number for the FF data, and compared my personal GEDmatch kit with theirs. The result was "No DNA match".

I have had reason to suspect there may have been a deviation in the line at either my mother or her father's birth. My question is, how definitive is this result? Essentially I am not a match for a close match to my 2nd cousin. Would this be common?

Thanks for your input.

I've bolded the part of your post which needs clarification for us to answer you.

You refer to a "2 generation spread" for this yDNA match and your cousin. Do you mean that the genetic distance (GD) of the yDNA match is 2? If so, this doesn't refer to how many generations separate the two from a common paternal line ancestor. The 2 refers to how many markers out of those tested that your cousin and the match differ on.

If the answer to my question in the previous paragraph is yes, the second question is at what level are your cousin and the match comparing - 25, 37 or 67 markers? If it's at 25 markers, then the common paternal line ancestor may have lived 2,000 years ago. Even at 37 markers, the common ancestor probably lived several hundred years ago. Both those "times to most recent common ancestors" (TMRCA) are too distant for an autosomal test to pick up any shared DNA. If your cousin and the match have a GD of 2 at 67 markers, then the common ancestor likely lived within the last few hundred years. In that case, an autosomal test might be able to pick up shared DNA, but there's a good chance it's still too distant to find enough shared autosomal DNA to declare a match.

[Leta]

Thank you for your responses. I apologize for the delay in getting back here. Apparently I am not receiving email notifications of responses. :/

I did misunderstand the meaning of the GD numbers, and I don't know why I said "2 generation". The GD is actually 0.

The account for the Y match is managed by his sister, and she does not have any tree information accessible so I will have to contact her by email to see if I can document traditional genealogical sources.

Both men took a yDNA67 test.

The default SNP on GEDmatch is 500. I changed it several times, going as low as 100. It still shows "No Shared DNA".

I will go back and follow up on the traditional research. Thank you for your help!

[spruithean]

What is the genealogical connection between these two men who are a genetic distance of 2?

[Jim Barrett]

Thank you for your responses. I apologize for the delay in getting back here. Apparently I am not receiving email notifications of responses.

This forum doesn't send out notifications of responses.

[KATM]

If you are a registered FTDNA forum member, you can subscribe to a thread or a forum, and choose the option to be notified by email. This is described in the FAQ (using the link at the top of each forum page), under "How to Use the Forums," then choose the link under "User Profile Features" for "Subscriptions."

[Jim Barrett]

Thanks for correcting me!

[KATM]

I didn't think it was possible, either, but took a look and found that it was. Not everything shown in the FAQ is enabled on this forum, but notifications seem to be.

[Leta]

What is the genealogical connection between these two men who are a genetic distance of 2?

That actually was a mistake on my part which I corrected in my most recent response. GD is 0. I have not been able to get into their tree to trace the genealogy. I am currently working on that. Thanks!

[Leta]

If you are a registered FTDNA forum member, you can subscribe to a thread or a forum, and choose the option to be notified by email. This is described in the FAQ (using the link at the top of each forum page), under "How to Use the Forums," then choose the link under "User Profile Features" for "Subscriptions."

Thank you!