Different results between Ancestry and MyHeritage DNA tests

Apologies if this has been raised before ... I had a quick look through the topics but couldn't find a heading that matched.

I originally tested with Ancestry DNA, and since uploaded my results to MyHeritage (and GEDmatch).

Yesterday, I received an e-mail alert from MyHeritage, letting me know I had a match with someone from interstate. He was my sixth "best" match, with 47.6cM, giving an estimate of 3rd-5th cousin.

I messaged him to discuss the match and got a quick reply. We are still working on where we match though I have a good guess. I asked if he had an Ancestry DNA profile as well, which he did.

When I went to Ancestry DNA and found his profile, it determined that we only had 7cM of shared DNA, and he was a distant cousin. While MyHeritage brings up several shared DNA matches, a couple of whom have the surname where I believe we may be linked, Ancestry does not bring up any shared matches.

My question is, have any of you had a similar situation? Do Ancestry DNA and MyHeritage DNA test different DNA segments to have these significantly different results?

(PS: the MyHeritage DNA result's largest shared segment was 22.4cM)

 

I raised a similar question back in 2017 which you can see here, and which may answer some of your questions.

Ancestry includes only 'close cousin' matches when we look at shared matches, and will not list those matches who are in our 'distant cousin list. While I can see that the list of shared matches could be impossibly long if all matches were included, it does mean potentially useful shared matches are omitted.

 

Many thanks Pauline!

 

I think the big question in the reported results is the difference in relatedness in the two different sets of results.

Someone can correct me if I am wrong, but I believe that each company only analyses some of our DNA as the entire code would be too much for systems to handle. And we can conclude that each company has chosen different genes to analyse and hence the different results for the same two people's comparisons. This no doubt then would flow on to each company concluding different ethnicity as well.

And it means that if the number of base pairs analysed by these companies were to increase, our ability to find matches further back would be increased.

 

Thanks, that explains why I have a match of 45 cM across 2 segments and my son has a match of 50 cM across 3 segments with the same person.

 

I find the cM are always significantly lower at Ancestry than other sites. I have a match of 94 cM at MyHeritage, whereas the same person is 66 cM at Ancestry.

 

That is very useful information Alexander. I have matches with a mother and son combination where the son matches with me for 43 cM over 3 segs but the mother is only 35 cM over 2 segs. I had assumed that must mean that the father is also related to me but had not tested. I have had a lot of difficulty trying to find out how he is related and now realize that he may not be after all and that I could be wasting my time. Thank you.