Closeness of Y-DNA matches

[Bazza43]

I'm trying to find something I once used on FamilyTreeDNA (I think -- it could have been on LostCousins.)

It allows you to go from the genetic distance and the number of markers to an estimate of the distance back of the most recent common ancestor.

For example, my one and only believable Y-DNA match has a genetic distance of 1 at each level he's tested (but doesn't match myself, my ROBINSON first cousin or my ROBINSON second cousin on Family Finder). THe numbers of markers are 12 to 67, and as I recall the likely number of generations back of the match is 8. I'm afraid I forget the suggested range, but I rather think it was 6 to 10 or 12 generations.

I'm now in the position of having to advise (female) colleagues who've had relevant male relations do the Y-DNA test, and have likely results in both cases at 111 markers. I think neither has matches as close as mine. Dorothy has a genetic distance of 2 at 67 markers (and 8 at 111.) Helen has 6-8 at 111 marker. BOth fit in with expectation of the place of birth of the earliest known male ancestor's parents.

Does anyone know of a place to find this information? I can't find anything on FTDNA any more about this.

 

[peter]

It IS at FTDNA - you need to click the TiP report icon and it will calculate the numbers for you. My closest match has a difference of 3 at 111 markers and there's an 84% chance that our common ancestor is in the last 8 generations, so I wouldn't expect there to be an atDNA match (though if he has tested it wasn't at FTDNA).

The chance of getting a Y-DNA match and being able to identify the common ancestor is currently quite low, but just knowing the surname of your matches is often a big help (because it can rule out the possibility of a NPE).

 

[Bazza43]

It IS at FTDNA - you need to click the TiP report icon and it will calculate the numbers for you. My closest match has a difference of 3 at 11 markers and there's an 84% chance that our common ancestor is in the last 8 generations, so I wouldn't expect there to be an atDNA match (though if he has tested it wasn't at FTDNA).

Thanks, Peter.

I was blowed if I could find the TiP Icon, but since you said I needed to click on it, I easily found it.

My report says I have an 89.79% chance of sharing a common ancestor within the last 4 generations -- well if it is within four generations, their paper trail to their Charles ROBINSON is wrong which I seriously doubt -- they are good researchers. And 98.96% chance within 8 generations, which I like. Joan (whose brother William did the Y-DNA test) has done both FTDNA and Ancestry DNA tests, like me.

I have just found a male ROBINSON descendant of the OTHER Charles ROBINSON (the one who's the son of William ROBINSON whom we think is ours) so I've dashed off a message to this man or his manager.

I will now dash off an email to Helen and Dorothy to tell them how to find the TiP icon.

Barrie

 

[peter]

My report says I have an 89.79% chance of sharing a common ancestor within the last 4 generations -- well if it is within four generations, their paper trail to their Charles ROBINSON is wrong which I seriously doub

If it was within 4 generations you would expect there to be an atDNA match (98% of the time, anyway).