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Autosomal DNA & Jane Starling

Autosomal DNA & Jane Starling

This week I learned quite a bit about autosomal DNA, that part that is not limited by gender, and that can help find cousins. Of course, there is much more to it than that, but this is how I keep all these terms straight in my own mind. Y-DNA are the genes linked to males, the X-chromosome, or mitochondrial DNA (mtDNA), are carried by both sexes, but females have two X chromosomes while males have one, from their mother. But we all have autosomal chromosomes, and in fact the vast majority of our DNA is composed of them. In fact, of the 23 genes tested by 23andme (see where that name comes from?), 22 are autosomal, and only one is comprised of X and Y chromosomes.

By Courtesy: National Human Genome Research Institute [Public domain], via Wikimedia Commons

By Courtesy: National Human Genome Research Institute [Public domain], via Wikimedia Commons

This image illustrates the proportions of the various chromosome types in human DNA. Each chromosome pair is made up of one gene from our father, and one from our mother. And while the 23rd pair seems pretty simple, being either Y-X or X-X (except in rare cases that we won’t go into here), it is really the other 22 pairs that enable us to inherit traits like eye, hair and skin color, potential height and body type, tendencies to develop certain diseases, and so on. They are also the genes that can be compared with other’s genomes to see if we are related to them, and if so, to estimate how close that relationship is likely to be.

And what does this have to do with Jane Starling? Well, as you can see in my last posting here, she is my great-great-great grandmother, whose background is a bit of a mystery. I expressed the hope that when my test results come in from 23andme, maybe they would tell me something about her “deep ancestry”, or what group of people she came from. We do know that she came to the U.S. sometime around 1830-45, but she may have gone to Canada first since on one census she told the census taker that is where she came from. On later census records she said she and her parents were born in Ireland. But if you know your Irish history, you know that just being born in Ireland does not say what your ethnic group is. There are Scottish, English, Norman, Welsh, French and who knows what else as well as Irish people there. In fact, Jane’s daughter married an Irishman who has a Welsh name, and whose mother also had a Welsh-sounding name, although his census records say he and both his parents were also born in Ireland.

After reading more about how genetic testing works, I decided to try to find some cousins who also have Jane in their direct maternal line. As it turns out, we have only two 2nd cousins who share this heritage with me and my sister. If we can persuade one or both of them to be tested and to compare their genomes with ours, we should be able to narrow down which traits we all inherited from Jane.

It will be six or seven weeks before my test report arrives. I wonder how many other family members I can talk into being tested by then?

OK, how many egregious errors have I made in this brief post? Do you have a genetic testing story? Tell us in the comments! And check our wiki, where the DNA section has pages for every heading now.

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