After having gotten my DNA tested I recently have had two matches who solely match me on the X Chromosome. To make matters worse both of those matches do not match one another. So I must assume they are from different contributors on my x chromosomes.
As you know a female inherits two x chromosomes, one from her mother and one from her father. This is where it gets complicated in that the one she gets from her father is the one he got from his mother; however, it may be given to him intact and whole or it can be recombined.
We know that the X chromosome is not the same thing as Mitochondrial DNA which leads a woman back to her mother and then her grandmother and then her great grandmother and so forth all the way back through her tree. All of a person’s ancestors do not contribute to the x chromosome, either.
Apparently from what I have read the x chromosome in females is inherited in the following manner. A woman inherits two x chromosomes, one from her father and one from her mother. The one she gets from her father was passed to him through his Mother. This is where it starts to get a bit more confusing because the x that she gave to her son is a combination of the x she got from both of her parents. Keep in mind that even though she got it from both her parents, it does not contain DNA from every individual in those specific lines, only specific ones. So, how do we determine which ones are the contributing factor to the X that a female receives from her father?
The first thing we need to do is to compile a chart. Since a Male can only get his X handed to him through his mother then we do not need to look at all of the males fathers, we quickly see we can eliminate some of those. As for the female the story is different, we must include both males and females in her because she gets one x chromosome from father and one from mother.
According to the Genetic Genealogistwebsite, in compiling chart that lists back to a person’s 5th Great Grandparents the following would be true:
There would be 128 Possible Ancestors at this level
· Males will have 21 potential contributors to their X chromosome which are comprised in the following way: 8 males & 13 females
· A female will have 34 potential contributors which are comprised in the following manner: 13 males and 21 females.
I have included the chart above for a Female; you may visit the site to find the chart for a Male as well.
You can also find an Ahnentafel chart that lists the potential contributors to the X chromosome at this link. This chart covers 10 generations. Males must begin the chart using their mother in the first space.
I have tried to list the main points that I have found out there while searching the web. If you would like to do some further research the websites I have listed above is a good starting point. You might also try Google using the term "X Chromosome Inheritance Female."
Let me end by saying this: I am not a Geneticist or an expert in the field. I am just an ordinary human being who is trying to make some sense of her DNA results. I will be sharing tips here on my blog of information that I find that I think would deem useful to my readers. Do your homework! And if I can give one tip, do it before you get those results back so that you are prepared when they do arrive! Best of luck!
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