Continuing That Thought

This is a follow up to yesterday’s post on ethnicity estimates using DNA. (YAWN!)

To finish up this topic (for now) let’s look at the ethnicity estimates of two of my siblings against mine.

From left to right we have my eldest sister, my brother, and my estimates. They are arranged by age, eldest to youngest.

It’s interesting to see the differences. Take the left hand image, my eldest sister. Less of England, Wales & NE Europe (hereby “British” – easier to type), by 10 points with me, but only one point with our brother. Both my siblings show more Africa than I do, as well as more Germanic Europe. My brother shows none of the European Jewish that my sister and I have. My sister’s estimate also shows Pennsylvania Settlers, that neither of us boys show. And that is very interesting; our paternal lines (both grandfather and grandmother) are well established in Pennsylvania.

How can that be? Well, “luck of the draw” is as good an explanation as any. All the results shown are from an Ancestry DNA tests, so they are autosomal (atDNA) tests. If you read yesterday’s post (and didn’t fall asleep), you will remember that atDNA tests looks at the first 22 pairs of chromosomes. This type of DNA is made up of about a 50/50 mix of the genes passed down from both parents.

But how much of your parents genes get handed down to each child? That’s where the “luck of the draw” comes in. Pick one of your parents, doesn’t matter which. They have their own 22 chromosomes, made of a 50/50 combo of their parents , which is made of a 50/50 combo of those parents.

It’s rather clear that you’re not getting all the genes from either parent. They can’t give you 100% of their genetic makeup and have it fit into 50% of your DNA. So which parts do you actually get from each parent? It’s totally random. The genes I inherited from my parents are not going to be the same as any of my siblings have inherited. Hence, different estimates. My sister received more the Africa DNA than I did, while I received more of the “British” genes. Guess that’s why I like IPAs?

You also have to consider that;

Almost all – 99.9% – of the DNA of any two people on earth is exactly the same. Accordingly, genetic genealogy tests are only interested in the 0.01% of DNA that can vary from one person to the next.

Genetic Genealogy in Practice, Blaine T. Bettinger and Debbie Parker Wayne.

An interesting site I didn’t mention in the last post, GEDMatch, allows you to upload the raw data from most of the popular testing sites for comparison with others. They also have ancient samples you can compare your DNA against. It helps if you’re interested in how much Neanderthal DNA you’re carrying around (current thought is everybody has 1% – 2%). You can also compare yourself to several archeological finds such as “Cheddar Man“. However, those examples are all mtDNA (mitochondrial DNA). mtDNA is the most common DNA that can be extracted from ancient finds. But is only passed down by the female line. So you can only know if your mother was related. But if she is related then you will be too.

Genealogy tidbit:
If your parents don’t have any children, there is a very high probability you won’t either.

And yes, we are full siblings. This image (with their names removed for privacy) shows the results. I didn’t ask the sister in the middle for her estimate, not that I don’t want it, I already had two good examples to use. And that image is hard enough to see!

Full siblings usually have around 2500 cM shared. We are well above that threshold.

I have used my beautiful and wonderful siblings data with their permissions. Of course, I did pay for all the tests, but the data is theirs, not mine. I thank them very much for allowing me to use it.

So, how many questions has this opened up? Has it intrigued you enough to do your own DNA test? If so, please research all the options including data privacy. Law enforcement is increasingly asking for DNA matches from all the companies out there. Where each company is headquartered greatly effects how much they share and the requirements of local and national law enforcement requests.

Peace,
B

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