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.