My Heritage DNA results

[geordiewesterby]

Does anyone know much about these results. My 2nd cousin and I (my Dad and her Mam were either full or half cousins, we are trying to establish which) have got a 2.3% match on the My Heritage DNA test. We knew there would be a match but we are trying to see how strong, as we think that my grandmother and her grandmother, who were effectively full sisters, were in fact only half sisters. Would that percentage match support that? I was working on the premise that (very roughly) siblings have about 50%, cousins 25%, 2nd cousins 12%. I know that's probably a primitive assumption but has anyone out there had experience of the results?

[Gadget]

My Heritage also gives the amount of shared DNA in cMs - e.g 450cM. Look at that measure and then consult :

https://dnapainter.com/tools/sharedcmv4

by either putting up the cM in the top box or by looking at the table below to see the range given for various measurements.

In relation to your % ~

I share 2.8% with a second cousin and 3.2% with a 1st cousin, 1 removed

Gadget

PS - cM = centimorgan

https://www.familysearch.org/blog/en/centimorgan-chart-understanding-dna/

[Gadget]

Scroll down to the Table  here:

https://isogg.org/wiki/Autosomal_DNA_statistics

Thia  gives the average amount by % and cM on average for each relationship


Gadget

[geordiewesterby]

Hi Gadget,

Thanks that's very interesting. It's 163.4 which the chart says is 52% probability of half 2nd cousins. The autosomal wiki chart is leaning towards half 2nd cousins as well. The other factor in this is that I have my Grandmother's wedding certificate from 1920 and the box for her father's name is left blank, while one of the witnesses was Thomas Drummond (who everyone in the family believed to be her father). She is named on the certificate as Charlotte Gilroy, her birth name. She's on the 1911 Census as Charlotte Drummond, but I guess she had just taken the name (or been given it as she was only 11 in 1911). The family story was that they got married after her birth, but it was actually 4 years after the birth and that was a few months before my 2nd cousin's grandmother was born so that looked like a rush to the altar. I think this result is just backing that up.

[Gadget]

It looks as if it is. 

53% Half 2C 2C1R Half 1C2R 1C3R
29% Half GG-Aunt / Uncle 2C Half 1C1R 1C2R Half GG-Niece / Nephew
 

You have to work with the DNA results and your tree and your matches trees.  I tend to work through my matches trees very thoroughly for mistakes as well.

I gave you a couple of my CM results (from MH) as they're proven relationships

Gadget

[Gadget]

I had a look at the entry on the 1911 that you referred to.  It's interesting that they were honest with the number of years married.

Do you have any matches with other Drummonds?

Gadget

[Gadget]

I've just looked at your earlier post about Thomas Drummond.

If Charlotte and Margaret were full sisters, you and your cousin should be full second cousins and your shared DNA would probably fall in the range 41-592 with an average of 229., so it's still possible to be full 2nd cousins (29% chance as opposed to 53% chance of being half second cousins.

As I asked on my previous post, do you have any other matches that might help you decide?


Gadget

[hurworth]

I've just looked at your earlier post about Thomas Drummond.

If Charlotte and Margaret were full sisters, you and your cousin should be full second cousins and your shared DNA would probably fall in the range 41-592 with an average of 229., so it's still possible to be full 2nd cousins (29% chance as opposed to 53% chance of being half second cousins.

As I asked on my previous post, do you have any other matches that might help you decide?


Gadget

My gt-grandfather had almost a dozen siblings.  Quite a few descendants of my gtgt-grandparents have tested and we've found a wide range of shared DNA. 

There's one match in particular who seems to share a low amount of DNA with his 2nd cousins - looking on MyHeritage he is sharing only 38cM with one of his 2nd cousins, 60 cM with their full sibling and 125cMwith their 1st cousin.  Yet when you look at all the other relationships from all the other siblings there's nothing to suggest anything is amiss anywhere. 

I suspect this match inherited more DNA from his English gt-grandfather, and he has some really useful matches up that line, and our branch inherited more from the gt-grandmother whose parents were Scottish.

[Gadget]

That's why Painter gives a wide range of shared DNA for each relationship