Funny Business at 67 Markers

[rms2]

Here's something interesting, speaking of 67-marker matches. Rick Arnold (GTCD2), who tested S145- (L21-) with Ethnoancestry, has a 60/67 match with Bryan Bonham (M2J8N), who tested L21+ with FTDNA. Rick is Bryan's closest match and vice versa.
 
So, what gives? Is it possible to have a 60/67 match in a different subclade? Or did either Ethnoancestry or FTDNA make a mistake? Using the rule of thumb of about 150 years per unit of genetic distance at 67 markers, Rick and Bryan shared a y-dna ancestor about 1,050 years ago. Even if we doubled that estimated TMRCA, that would only get us back 2100 years. And I don't think anyone believes L21 is quite that young.
 
My conclusion is that Rick and Bryan are either BOTH L21+ or BOTH L21-.
 
(Hope they don't mind me talking about them!)

[susanrosine]

Do you know if either or both of them are going to get retested?

[rms2]

Do you know if either or both of them are going to get retested?

Both of them are considering that right now.

[GoldenHind]

I'm not sure I would totally rule out the possibility of convergence, nor would I be surprised if one of the labs made an error. I hope they both re-test.

[rms2]

I'm not sure I would totally rule out the possibility of convergence, nor would I be surprised if one of the labs made an error. I hope they both re-test.

Convergence is a possibility, I guess, and it did occur to me. But it seems it would have to be pretty extremely coincidental to bring the two men within a gd of 7 of one another.

I know Rick is thinking of ordering the L21 test from FTDNA, since his original test was with EA.

[vineviz]

A 60/67 match across R1b1b2 subclades is not unexpected and this is not even the first time I've seen such a thing reported.

However, I think you would better describe this as "lack of divergence" rather than convergence since the MRCA haplotypes for most common clades appear to have been 60/67 or closer to start with.

VV

[rms2]

A 60/67 match across R1b1b2 subclades is not unexpected and this is not even the first time I've seen such a thing reported.

However, I think you would better describe this as "lack of divergence" rather than convergence since the MRCA haplotypes for most common clades appear to have been 60/67 or closer to start with.

VV

Yeah, you're right. It's a bit unnerving, though.

Apparently now Rick has tested L21- with both EA and FTDNA, so it doesn't seem likely the error (if there was one) is with his sample.

[vineviz]

Yeah, you're right. It's a bit unnerving, though.

I can see how it might be.  But with the R-P312 modal and the R-L21 modal being a 66/67 match, it is not surprising there would be considerable haplotype overlap.

VV

[chris1]

A 60/67 match across R1b1b2 subclades is not unexpected and this is not even the first time I've seen such a thing reported.

However, I think you would better describe this as "lack of divergence" rather than convergence since the MRCA haplotypes for most common clades appear to have been 60/67 or closer to start with.

VV

I've been puzzled about this. What process might cause this "lack of divergence" for some haplotypes in different subclades?

[Jdean]

I've been puzzled about this. What process might cause this "lack of divergence" for some haplotypes in different subclades?

A subject I've often wondered about myself, I have a GD of 0 at 37 with a person sharing my name were there should be no chance of a connection within the last 250 yrs at least, they’re in the US were as I’m in the UK, conversely we have another two people with a paper trail going back to about 1725 with a GD of 4 at 37, I might add that the name is not that common, there are only 17 people with it in FTDNA's database.

[vineviz]

I've been puzzled about this. What process might cause this "lack of divergence" for some haplotypes in different subclades?

Nothing really causes it, per se.  It just so happens that some lines of descent have had (by chance) fewer mutations than other lines or even than the average line.

If you give 100 men a coin, and have each one flip it one hundred times then most of them will end up with something close to 50 heads and 50 tails.  But, by chance, some of them will end up with significantly less than 50 heads.

Likewise, in a large group of men most of them will have haplotypes that have diverged from their 100-generation-ago ancestor by a decent amount (a GD of 10 to 15, for example). But some will diverge much less, while others will diverge much more.  It's really just luck.

VV

[GoldenHind]

Yeah, you're right. It's a bit unnerving, though.

I can see how it might be.  But with the R-P312 modal and the R-L21 modal being a 66/67 match, it is not surprising there would be considerable haplotype overlap.

VV

Could someone please tell me what the single difference is between the P312 and L21 modals?

[vineviz]

Yeah, you're right. It's a bit unnerving, though.

I can see how it might be.  But with the R-P312 modal and the R-L21 modal being a 66/67 match, it is not surprising there would be considerable haplotype overlap.

VV

I think it was at DYS449,  though I don't recall off the top of my head which clade had which value.

VV
Could someone please tell me what the single difference is between the P312 and L21 modals?

[Jdean]

I've been puzzled about this. What process might cause this "lack of divergence" for some haplotypes in different subclades?

Nothing really causes it, per se.  It just so happens that some lines of descent have had (by chance) fewer mutations than other lines or even than the average line.

If you give 100 men a coin, and have each one flip it one hundred times then most of them will end up with something close to 50 heads and 50 tails.  But, by chance, some of them will end up with significantly less than 50 heads.

Likewise, in a large group of men most of them will have haplotypes that have diverged from their 100-generation-ago ancestor by a decent amount (a GD of 10 to 15, for example). But some will diverge much less, while others will diverge much more.  It's really just luck.

VV

So it boils down to That's Life

That's quite funny