Wednesday 10 October 2018

So, where's my sister from then?

We may look alike, but we are not the same. Not on the outside...
... and not on the inside
On the same day the results of my mother came in, both my sister and I got our results as well. They varied, which to me sounded very strange. Surely as sisters we should have the same DNA! My sister works with DNA and such, but could not give me a proper answer immediately. She knows, but needs to put it in simple person talk for me.

Fast forward to today and I got an answer to the conundrum, albeit not from my sister. In short it's like this: Even though you get half of your stuff from one parent and the other half from the other, it doesn't necessarily mean you get exactly half of everything. It is completely random what you get in fact. Here's an example:

My paternal grandparents
Grandfather A is 100% German and grandmother A is 50% Italian and 50% Scottish. They produce child A which is 50% German, 32% Scottish and 18% Italian.
Grandfather B is 50% Irish and 50% Scottish and grandmother B is 100% Italian. They produce child B which is 50% Italian, 36% Irish and 14% Scottish.
Child A and child B have two children. Child 1 is 41% Irish, 32% Italian, 27% German and 0% Scottish. Child 2 is 50% German, 18% Italian, 18% Irish and 14% Scottish. 

My maternal grandparents
And that is exactly what happened to my sister and myself.
My own results show that I am 44% Germanic (mainly Dutch), 34% England/Wales/Northwestern Europe (mainly English), 17% Norwegian and 5% Swedish.
My sister's results show that she is 44% England/Wales/Northwestern Europe (mainly English), 26% Germanic (mainly Dutch), 18% Norwegian, 9% Swedish and 3% Irish/Scots. 
Which means that I am more Dutch than my sister, yet she is more Viking than me.

Me, my sister and my brother
Now, we have a brother as well and were he to do this test, his results will be completely different again, although the results will point out to us that there is a high likelihood that we are related in the first degree (ie siblings), regardless of differences. 

PS: had my sister and I been identical twins, the results would have been the same. And if for some reason the results had been the same now, it would have been a complete fluke really.

PS2: the explanation was given by Marc McDermott, who is the founder of Genealogy Explained. He wrote a guest blog for MyHeritage, one of the genealogy sites. Even though we did our tests with Ancestry, the explanation is the same for all tests.


  1. Hari Om
    It's fascinating stuff... and makes sense insofar as we tend to say "S follows mother's side and T follows father's..." just from visual and personality. YAM xx

    1. It IS fascinating. I didn't even realise how fascinating until now!

  2. Very interesting. Just shows what a mixture we all are.

    1. And yet, they still seem to be able to tell that my sister and I are related! Despite the differences in our mixtures.

  3. That's very interesting! Ghostwriter says all four of the siblings have a different blood type. What are the odds of that? Yesterday she met a new nurse's aid at work. She looks exactly like another aid (I mean spitting image!) It was amazing that the two aren't related!

  4. That's very interesting. We can tell by looking at you and your sister that you are related so you certainly have some part that are the same.

  5. This is amazing I had no idea...
    No telling what my DNA would say. LOL
    No matter with you and Gera you are both from excellent DNA and for sure look like siblings as adults. I think you resemble your maternal Grand ma and she for sure has Paternal Grandmas mouth.
    Hugs C

  6. Thank you for explaining this. Extremely interesting!

  7. Well, this was certainly weighty, although definitely fascinating. I used to think it was a whole lot simpler. One grandmother provided 25% of my DNA, the other grandmother 25 %, and each grandfather 25%. Boy, was I wrong. Thanks for the information, Mara. I might just look into it when my brain is better. Meanwhile, it continues to progress. Whew!

  8. That makes complete sense to me.

    1. It does? I had to read it twice before understanding everything. And I am still not sure whether I understood it completely!


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