Ancestry DNA shared matches - bug?

[Gadget]

Yes, that's the one - Replies #13-16. 

Thank you, Steve 

Gadget

[hurworth]

Correct - shared matches are only people you share at least 20 cM with and the other person also does.

I have access to a few kits at Ancestry and the number of mutual matches from particular lines certainly decreases as you go down the generations, but often they are still matches.

For this reason, if you'd really like to get the most out of your DNA test I'd recommend uploading anywhere you can such as FamilyTreeDNA, Gedmatch and MyHeritage and you may still match. 

[Gadget]

I uploaded mine to the other sites as soon as I got my Ancestry results and have managed to get some of my matches to do the same.

I particularly like the My Heritage shared matches as it gives both your shared cM and the match's shared cM with each of your shared matches. Gedmatch also does this but I've only found a few close matches on there.

Gadget

[melba_schmelba]

Hello Gadget,

Were you thinking of this thread?
https://www.rootschat.com/forum/index.php?topic=801386.0

Page 2 has some mention of folk below 20 cMs not showing in shared matches.

Steve

I think it was a confusion between Gadget saying she wasn't finding any shared matches on her 5th-8th cousins (until then), and others stating Ancestry doesn't show any 5th-8th cousins on the shared matches at all, which I am now sure is correct, as I have a certain group of matches with a huge number of shared matches (probably Mormons) and they stop straight at 20 centimorgans 4th-6th cousins. I am not sure why they draw this arbitrary line, so it doesn't put too much strain on their servers, because too many shared matches would confused people? Either way it seems a bit annoying as I am trying to draw up little tree maps trying to work out which groups of matches come from where, and now it seems I am probably missing most of these under 20 centimorgans unless I find them with a surname search or shared ancestor hint .

[lisalisa]

I think it was a confusion between Gadget saying she wasn't finding any shared matches on her 5th-8th cousins (until then), and others stating Ancestry doesn't show any 5th-8th cousins on the shared matches at all, which I am now sure is correct, as I have a certain group of matches with a huge number of shared matches (probably Mormons) and they stop straight at 20 centimorgans 4th-6th cousins. I am not sure why they draw this arbitrary line, so it doesn't put too much strain on their servers, because too many shared matches would confused people? Either way it seems a bit annoying as I am trying to draw up little tree maps trying to work out which groups of matches come from where, and now it seems I am probably missing most of these under 20 centimorgans unless I find them with a surname search or shared ancestor hint .

I'd like the shared matches to go further/lower than 20cMs, but probably not so low as to catch all those at 6.  Maybe a lower limit of 10cMs would be my choice at the moment, (though that could of course change depending on what I was trying to work out).

Now if we could choose what the limit would be (some kind of sliding scale), that would be very good.

[Gadget]

Most of the other sites go below the 20cM level. I think Ancestry uses the cut off because of the vast number of cases in their database and they're still hoping to make family history  'fun' for new subscribers (whatever that means!).


Gadget

[melba_schmelba]

I think it was a confusion between Gadget saying she wasn't finding any shared matches on her 5th-8th cousins (until then), and others stating Ancestry doesn't show any 5th-8th cousins on the shared matches at all, which I am now sure is correct, as I have a certain group of matches with a huge number of shared matches (probably Mormons) and they stop straight at 20 centimorgans 4th-6th cousins. I am not sure why they draw this arbitrary line, so it doesn't put too much strain on their servers, because too many shared matches would confused people? Either way it seems a bit annoying as I am trying to draw up little tree maps trying to work out which groups of matches come from where, and now it seems I am probably missing most of these under 20 centimorgans unless I find them with a surname search or shared ancestor hint .

I'd like the shared matches to go further/lower than 20cMs, but probably not so low as to catch all those at 6.  Maybe a lower limit of 10cMs would be my choice at the moment, (though that could of course change depending on what I was trying to work out).

Now if we could choose what the limit would be (some kind of sliding scale), that would be very good.

Yes that would be good, but I can't see ancestry allowing us that as they don't seem to allow any other kind of tweaks, seems like it is GEDMATCH we will have to rely on for more flexibility.

I was just about to ask what benefits the Tier 1 ($10/month) version of the GEDMATCH one to many tool offers when I found this slideshow from Kitty Cooper:

http://slides.com/kittycooper/gedmatch-10-13-17#/1

Slide 12 onwards shows what you get with the Tier 1 One to Many DNA comparison

http://slides.com/kittycooper/gedmatch-10-13-17#/12
Although it appears GEDMATCH Genesis may have improved it again as it is now labelled 'Enhanced'

It appears there may not be a 3000 match limit as there is on the free one, and also you can search down to 3 centimorgans but it advises the smallest segment you should go down to is 7. You can select multiple criteria boxes.

As an aside, has anyone noticed the Genesis match doesn't yet display GEDCOM tree links ?

[stevemiller]

I came across this yesterday, as one way to get at some of your 5-8 cousins.

http://www.rootschat.com/links/01naz/

My 1st cousin and I have now shared our results, and it is very useful.

[melba_schmelba]

I came across this yesterday, as one way to get at some of your 5-8 cousins.

http://www.rootschat.com/links/01naz/

My 1st cousin and I have now shared our results, and it is very useful.

Thanks Steve, yes I was aware of that trick, It's a quick way of seeing if you match someone, but as I mentioned earlier in the thread, it looks like Ancestry's Timber algorithm may be filtering out actual matches erroneously that do show up on GEDMATCH and other sites. You can also obviously just trawl through your shared match list, but you still don't know how many shared matches from 6-19.9 centimorgans you may be missing, until you've gone through the 25,000+ matches one by one!