Surprised at differences in DNA Matches between siblings

[jillruss]

I know I shouldn't be surprised, but I am!

Just got the matches through for the DNA test I got my older brother to do (managed by me). Yes, there are many matches akin to mine but there are so many new ( to me) names on his list - even in the 'high prediction' of 4-6 cousin - that, quite frankly, if it wasn't that I'm his top match and our niece is his second top match, I'd be questioning his parentage!!

Of course, I knew about the roughly 50% of mother's and 50% of father's DNA inheritance thing, and I suppose, theoretically, its almost possible for us not to have any of the same DNA, but I'm still very surprised. I've been delving into my own matches for about 9 months now so am pretty au fait with most of the names, but I've never heard of a lot of my brother's 'good 4-6' matches.

This is good news, of course, for me trying to find 'new' cousins but - and I know I keep saying (typing?) this - its still a shock! e.g. one of my 'good' and established matches at 28.3 cMs is only showing as a 13.8cMs match on my brother's list. There are lots of other such examples.

I bought another kit in Ancestry's Boxing Day sale and am persuading another brother to do the test. This is becoming addictive!

Jill

[sugarfizzle]

Jill, Just goes to show the differences. Neither of my brothers are interested in DNA testing - they might if I paid for it.

A cousin has, and I am surprised enough by the differences in our matches, can see where her father must have inherited very different DNA than my father from their parents.

That's why they say, test as many people as possible.

Regards Margaret

[Gadget]

I've just discovered something similar but different.

My great nephew and I both match a 3rd cousin, However, his mother, doesn't match the cousin, although she matches others that are shared, as does the cousin 

The 4rd cousin's results were put up a week before my niece's. Might it be that these latest  tests haven't been fully matched yet?


Gadget

[sugarfizzle]

Gadget

As far as I am aware, results are fully matched before they are released.

Regards Margaret

[Ayashi]

I think I was told at one point that it could take 30 days for results to be fully matched with each other. I also think that the "Shared Match" function is a bit dodgy either way, but I can't prove that one.

[AlanBoyd]

According to information at Ancestry the probabilities of a shared match for 4th, 5th and 6th cousins are 71%, 32% and 11% respectively. If my rudimentary knowledge of probabilities is correct this means that the probabilities of sharing a specific match with a sibling at each of these levels are (with aggressive rounding):

4th cousin – 50%

5th cousin – 10%

6th cousin – 1%

[sugarfizzle]

Gadget, Have you access to your niece's DNA results, or are you relying on shared matches?

If the former, you should be able to confirm definitely whether your niece matches or not.

If the latter, then maybe check again in a month.

As I said before, I don't think this is the case that shared matches are delayed, but happy to be proven wrong if your niece suddenly appears as a match.

Let us know what happens.

Regards Margaret

[Gadget]

I've asked her to let me have her details (password) etc. and to upload to Gedmatch (as 3rd cousin is on there too) but she's had very big probs this week, so I'm relying on the shared matches.

Matches with other lines seem to be as expected. Also, niece matches with some others on that line who share similar cM with me 

I've done them between my results and each of the other 3 individually. I'm surprised that her son (grt nephew) is a match but she isn't. 

I'm wondering if because 3rd cousin and niece have only just had their results means that Ancestry haven't fully done the run through.

Gadget

[Ayashi]

My conversation with Ancestry:

Me: "I have a question regarding the DNA function on the website. After scrolling through new matches I found someone who I might be able to prove a match with. I contacted her and asked her if she could use the "search matches" function for particular surnames to see if she was related to certain cousins of mine, to narrow down where our link was. She couldn't find any of the names I gave her. That could be suggestive of our suspicions being wrong, but when when I used the function to find her account, I was getting no results for surnames I knew very well were in her tree (and subsequently had to scroll through the general list again to find her). I was wondering why this would be the case? If this function isn't working properly then it rather scuppers a lot of my matching tactics. Thanks"

Anc: "Hi (Name), the feature is working properly, it can take up to 30 days after the results come in for matches to completely show in results. Are you or (Name) new to DNA?"

Me: "She only uploaded in the last couple of days, so she is new. My account might be over 30 days now. I find it odd though that she would be matched in results but the search function to not find her surnames. Why would that part of the matching take longer?"

Anc: "Hi again (Name), the indexing behind the search functionality can take some time to populate matches and that is likely why that aspect of the matches section is taking longer, we apologise for any frustration that may be causing during this time."

So according to this person, it does take a while for things to fully work.