Significance of 25-marker match

[Mark Bridge]

I recently received my Y-111 results. I have only one match who shares my surname. His earliest known paternal-line ancestor, born in the early 19thC, was from Lancashire, about 12 miles from where my earliest known paternal-line ancestor lived in the 16thC. My match took the Y-37 test, but does not match me at the 37-marker level - he is only a match (an exact one) at 25 markers. I suspect that if we are related, our most recent common ancestor lived during or before the 16thC - the surname is recorded in the area from the 13thC, though it may have been used by several unrelated families. However, I'm not sure whether the fact that we do not match at 37 markers rules out any relationship within a historical timeframe, i.e. the 25-marker match is likely to reflect shared ancestry before the adoption of surnames(?) For context, I have other matches at 25, 37 and 67 markers who do not share my surname - with a minimum genetic distance of 3 on my 37-marker matches and 5 at 67 markers.

I'm curious about this because my family moved from England to Ireland in the 17thC and meaningful matches with other Bridges with origins in Lancashire would help to rule out an NPE in the subsequent centuries - and also highlight connections to other family branches. I would be grateful for any steers on this, though I realise that it might require Big Y testing of a number of descendants to provide useful insights.

Best wishes,

Mark

[georgian1950]

So, you had no matches at Y-111?

[Mark Bridge]

Yes - no matches at Y-111.

[mabrams]

If you don't match at 37 markers, that almost seals the 'no-deal', since in my experience, most 33/37 tests seem to be coincidental or from a long time ago. And typically, your genetic distance grows as more markers are added.

but.....so you don't throw in the towel....

I have a match (we do not share a surname) at 12 out of 12 who then descends to a marginal 23 out of 25. He then disappears at 37 and 67 and but pops up back at Y111, albeit barely. 101 or 102 out of 111. However, he is also a BigY match, where we are only one subclade apart.

So non-matches can become matches at higher levels, although that is certainly bucking the normal trend.

This is FTDNA's take on low-level matches at 37 markers. Although I think it is from an older viewpoint. Read the part at 31 or 32 about "in-betweeners"
If two men share a surname, how should the genetic distance at 37 Y-chromosome STR markers be interpreted? – FamilyTreeDNA Learning Center

You are not really going to know for sure, unless you can convince your 25/25 mate to test to a higher level and/or both of you take some level (very optimally BigY) of SNP testing.

[Mark Bridge]

Many thanks for your response - it's very interesting and helpful. I'll think about broaching Big Y testing with my 25/25 match. I'm awaiting my own Big Y results so will see if they throw up any more promising leads first, given the likelihood that the same-surname match is not a meaningful one.

Best wishes,

Mark

[georgian1950]

I have a match (we do not share a surname) at 12 out of 12 who then descends to a marginal 23 out of 25. He then disappears at 37 and 67 and but pops up back at Y111, albeit barely. 101 or 102 out of 111. However, he is also a BigY match, where we are only one subclade apart.

That is remarkable, Maybe I should reconsider my policy of not looking at anything under Y-37.

I have told this on other threads, but I will go head and repeat. When I tested Big Y 700, I had around five Y-111 matches. However, the person who I formed a new terminal SNP with, only matched me at Y-67.

Mark, I see where you have already tested Big Y. I think that is great, and the results should be helpful in seeing who to encourage to upgrade also.

[mabrams]

Georgian1950
I dont mean to mislead you about Y12s and Y25s. IMHO, of minor significance, since they dont show up ever again (except the 101/111 gent)

I have 3 close BigY-Y111 matches. But three other BigY matches are Y12 only and two are not even that. So the last 5 are extremely distant. 1700 to 2300 years ago. Even the 101/111-BigY match is estimated at 900 years ago.