X c'some confusion, please help!

[Annie65115]

I have a moderately distant (prob 150 - 200 yr ago) match with 3 living members of the same family; 2 men and a woman.

All 3 match with me for a decent stretch on chromosome 5. However only the female shares an X c'some match with me as well.

Does this signify that our match is from their paternal line, or not?

<<<confused>>>

[Neli]

Sorry I am no help but, the whole X thing confuses me too. I've read lots about it but nothing seems to clarify whether X links are worth investigating. I always think scientists are vague and use lots of gobbledegook language when they aren't quite sure themselves :-)

[Spike H]

Assuming you are a female.....you receive an X chromosome from each of your parents.
Your mother received her X chromosomes from each of her parents. Your father received his single X chromosome from his mother . And so it goes.
There is a specific inheritance pattern for the X chromosome. You can create an X-tree starting with yourself and working back those 150 to 200 years. Your father's father will not be in it neither will your maternal grandfather's father. The X chromosome is not passed from male to male so all those lines are removed going backwards.
If you have all the relationships going back all those years and the other person does as well, you will be able to find the common ancestor.

This inheritance diagram is included on the following blog by Louise Coakley and includes a downloadable template.
http://www.genie1.com.au/blog/63-x-dna

[Neli]

I kinda get that bit Spike but, and, sorry Annie for hyjacking your post, what I don't get is if I have relatively small overall link with someone on Gedmatch, just 7+ but, a relatively high X match 30+ does the X match mean anything? I also have some fairly high X matches with 0 general matches, is that a match of any sort?

[pharmaT]

I kinda get that bit Spike but, and, sorry Annie for hyjacking your post, what I don't get is if I have relatively small overall link with someone on Gedmatch, just 7+ but, a relatively high X match 30+ does the X match mean anything? I also have some fairly high X matches with 0 general matches, is that a match of any sort?

If that person is a man you match on their mothers side.  If you are both female then you can narrow down the match to lines in the diagram above.

[hurworth]

Unless it's a whopping great big matching segment I'd not make any assumptions about which side it is from.  30cM is quite large, so it may well be a maternal match.

A couple of kits I manage (females) match several 3rd cousins who are 3rd cousins via their paternal grandfather.  The only X-DNA these females would have received from their paternal side had to come from their paternal grandmother, NOT the paternal grandfather. 

However they share some smallish segments of X-DNA with a couple of these 3rd cousins.  So, somehow, there is some other relationship between them as well.

[Annie65115]

I have a nearly-30cm-segment on the X c'some with a man with whom I have confirmed our shared ancestry, and I rather like the idea that that bit of my DNA comes from my ancestor Rebecca

(it has to be from her since we both have it, he's a man, and we're both descended from her - she is our shared ancestor, and as can be seen from the charts above, he could ONLY have inherited it from her, not from her husband).

But this other link, about whom I started this thread, is about a different sequence on the X and a different family and the more I think about it, the more I think that its absence on the males on this family means nothing in terms of where it came from. I think that segments on the X chromosone, when present, can help (as in my ancestor Rebecca) but their absence doesn't mean a thing.

[Spike H]

But this other link, about whom I started this thread, is about a different sequence on the X and a different family and the more I think about it, the more I think that its absence on the males on this family means nothing in terms of where it came from. I think that segments on the X chromosone, when present, can help (as in my ancestor Rebecca) but their absence doesn't mean a thing.

Annie, it is quite rare for males to have X-chr matches, so I think you are correct in what you are saying. I have only three matches, but one is with another male and it is a somewhat astonishing 40cM's. I sent my X inheritance names off to his admin and found that we both matched to my great grandmother's father's mother bpt 1807. From there it was a doddle to confirm the relationship on paper.

[Annie65115]

Unless it's a whopping great big matching segment I'd not make any assumptions about which side it is from.  30cM is quite large, so it may well be a maternal match.

As a DNA newbie, I'd be interested to know how big a segment has to be to be considered a "whopping great big one" (I know that sounds silly but it's a genuine question!)

ta