# Thread: how to determine lineage

1. ## how to determine lineage

How to figure out this problem: mother/daughter tested, both have of course X chromosome (haplo is D4). On Gedmatch largest X match was of different haplo T1. Having X matches but have completely different haplgroup? Can someone help me to understand it ?

2. Significant X match for a woman need not have the same haplo, because X match and mtDNA are different.

For example, mother and daughter share mtDNA AND are an X match.

Daughter and father do not share mtDNA but are an X match (daughter gets X from both parents).

Here, the daughter and mother both match another person, but the other person need have gotten his or her matching X segment from someone sharing a matrilineal line with them. For example, the mother and daughter have a matching X segment from the mother's father, someone with whom they would not have an mtDNA match. If the other person matched is a woman, that person's matching X segment could be from her father, so again would not go with matching mtDNA.

You can simply rule out that this person is a matrilineal match.

Hope that makes sense.

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MikeWhalen (08-12-2019)

4. The same thing is true for males. Although my eldest brother inherited both his mtDNA haplogroup and his single X chromosome from our mother, she didn't get both from the same source.

Like everyone else, of course, she inherited her mtDNA haplogroup from her mother. But the X chromosome she passed on to my brother contained DNA only from her father. In other words, she passed on an unrecombined copy of the same X chromosome she inherited from her father -- which he, in turn, inherited from his mother.

This is not the only time she passed on an unrecombined X, either. One of my sisters also inherited a maternal X chromosome with no contribution from our grandmother. As a result, her X chromosome has half identical matching with our brother across the entire chromosome.

My own X does contain some DNA from our grandmother, though not much: only about 20 cM surrounding the centromere. The rest is from my maternal grandfather.

One way the X chromosome can be very useful in genealogy is that it has vastly fewer possible contributors as compared with other chromosomes. It can be helpful to fill out a chart like the one found here. Just remember, not everyone who is a potential contributor to the X chromosome will necessarily be an actual contributor.

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MikeWhalen (08-12-2019),  spruithean (01-07-2018)

6. Originally Posted by msmarjoribanks
Significant X match for a woman need not have the same haplo, because X match and mtDNA are different.

For example, mother and daughter share mtDNA AND are an X match.

Daughter and father do not share mtDNA but are an X match (daughter gets X from both parents).

Here, the daughter and mother both match another person, but the other person need have gotten his or her matching X segment from someone sharing a matrilineal line with them. For example, the mother and daughter have a matching X segment from the mother's father, someone with whom they would not have an mtDNA match. If the other person matched is a woman, that person's matching X segment could be from her father, so again would not go with matching mtDNA.

You can simply rule out that this person is a matrilineal match.

Hope that makes sense.
Help?!?!?! Please Help?!?! I didn't want you to think I was being rude. My dad's 2nd or 3rd cousin just tested at FTDNA. She is a Webb, a descendant of my great grandfather's sister, which means she is a crucial match because my Webb line is the one where my great grandfather's father is a mystery. My dad's first cousin already tested at FDTNA a few years ago so now I can triangulate. While using the chromosome browser tool, I expanded to 1+ centimorgans and this new match, 2nd or 3rd cousin to my father shares 2.1 cm on the X with me. Is this normal? Is there anyway to use this to help me determine which line my X comes from? Thanks.

7. Originally Posted by Webb
Help?!?!?! Please Help?!?! I didn't want you to think I was being rude. My dad's 2nd or 3rd cousin just tested at FTDNA. She is a Webb, a descendant of my great grandfather's sister, which means she is a crucial match because my Webb line is the one where my great grandfather's father is a mystery. My dad's first cousin already tested at FDTNA a few years ago so now I can triangulate. While using the chromosome browser tool, I expanded to 1+ centimorgans and this new match, 2nd or 3rd cousin to my father shares 2.1 cm on the X with me. Is this normal? Is there anyway to use this to help me determine which line my X comes from? Thanks.
I'm sorry to say that a match of this size is really too small to be considered meaningful. It might reflect distant relatedness, but by "distant" I'm talking about possibly being well beyond any genealogically-significant timeframe. Potentially dozens or more generations. We're all related at some point.

In any case, your father's X chromosome came from his mother, and only his mother.

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Webb (08-08-2019)

9. Originally Posted by Webb
Help?!?!?! Please Help?!?! I didn't want you to think I was being rude. My dad's 2nd or 3rd cousin just tested at FTDNA. She is a Webb, a descendant of my great grandfather's sister, which means she is a crucial match because my Webb line is the one where my great grandfather's father is a mystery. My dad's first cousin already tested at FDTNA a few years ago so now I can triangulate. While using the chromosome browser tool, I expanded to 1+ centimorgans and this new match, 2nd or 3rd cousin to my father shares 2.1 cm on the X with me. Is this normal? Is there anyway to use this to help me determine which line my X comes from? Thanks.
Yeah, it's normal and as geebee says it's meaningless. That size match can be just coincidence, and need not indicate any connection at all (and here it would not).

I had a similar thing since FTDNA indicates an X match even where the match is super tiny. My dad has a match who unquestionably is from his paternal side, yet had X match listed, so I was worried for a while it might be an "on both sides" match (the match with my grandmother would have to be very very far back, as the match was in the UK). Finally I realized that the X match was likely not a real match. That's why they have the default 5 cM on the chromosome browser, I assume.

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MikeWhalen (08-12-2019),  Webb (08-12-2019)

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