X-DNA: What is the minimum reliable cM to research? | Genetic Genealogy

[@sr2291]

I wish more of the DNA testing companies would report the X DNA results.

[@suzannemcclendon]

I have an interesting puzzle with one of my DNA matches. She matches me through both my father and my mother. She has a 20+cM X-DNA match with me and my mother on the X, but doesn't have an autosomal match to my mother. She does, however, have an autosomal match to my father (and no X match to him). No names in her tree are familiar to me, so this is going to be a fun one to sort out. Also, it appears that my paternal X-chromosome has been passed down intact at least as far back as my 4th great-grandmother, through my grandmother's father, from her to her son to his daughter to her son to his daughter to her son to me. There is so sign of "interference" from the other half of the ancestor couples involved. Keep up the good work!

[@roberthopgood1894]

where are the dna basics videos so i have a chance of understanding this

[@FamilyHistoryFanatics]

I finally made a basics video playlist. kzbin.info/aero/PLcVx-GSCjcdnEg-YtkXA7Nj2YxxamaYKA But... X-DNA, mt-DNA, and y-DNA are not easy to learn. Instead, focus on autosomal DNA.

[@roberthopgood1894]

@@FamilyHistoryFanatics thx

[@jasonjoseph8700]

Thanks for sharing something I totally didn't Know about, that part

[@godisloveireland]

Enjoy your trip devon!

[@FamilyHistoryFanatics]

I did.

[@lauraneville50]

excellent presentation-- thank you so much!

[@FamilyHistoryFanatics]

Glad it was helpful!

[@LindaSchreiber]

I usually have a minimum of 20 cMs for someone with reasonable autosomal (25 or better). For someone with no autosomal and 35-50 on the X, I will at least do some looking. Some of those are id-able. But I don't drive myself crazy over them ;)

[@michaelwhalan9783]

Four Geiszler X matches only at about 24cM on one segment each 23andme then one autosomal at 8cM on MyHeritage (they don't show X).

[@vinicius.lavandoscki]

Would a 7.3 cM autosomal + 33 cM X DNA match be relevant on searching ? Since i'm adopted i think it might help me figure out my maternal line.

[@LanceHall]

My cousin matches a 6th cousin on chr 1 (10cm), chr 2 (10cm) and chr 23 in two places (6.1 and 7.6). Yes, they would share X-DNA from the common ancestor. So, I assume this is a legit X-DNA match or a match on other lines not yet known?

[@FamilyHistoryFanatics]

The amount of X DNA shared is still quite low. I would have to find the common ancestor before I would say it is a "legit" match.

[@ericpham5198]

If we calculate all the way to beginning of humanity each one of us may had up to hundred thousand of relatives I other universe like tree , flowers or other living physical or spiritual

[@FamilyHistoryFanatics]

While theoretically that's a fun exercise, that's not how genetic works. kzbin.info/www/bejne/pJ3QfGOOaK5kgtE

[@jonathanlong5504]

I found a well-triangulated X DNA segment for a distant ancestor, and I am wanting to contact the other folks who appear to share at least part of the same segment (start or end). The triangulated matches do not share autosomal DNA, but I have connected their trees via X inheritance pathways. It seems that a 15 cM limit (and the required autosomal rule) would be too restrictive once you have identified the segment in this way. I recognize that most people won't have trees that go far back enough to confirm a connection, but I am concerned about avoiding false positives. Do you have a sense for what the limit should be to avoid that problem?

[@sharonjacob4782]

Interesting Andy the only platform I am on that shows a X chromosome match is FTDna but it's always attached to an autosomal match. Perhaps I didn't catch it but did you state that the x chromosome division always happens as you demonstrated with the maternal x chromosome coming from grandparents always the female side donating 13 and 13 and none from the make side at that level? And that is how you can eliminate for sure that line of ancestors?

[@lbfaith]

How do I go about placing an female 2nd cousin (1C1R) adoptee that matches with a male using x dna? Or the chromosome browser?

[@FamilyHistoryFanatics]

The male has to be related to the female through the male's mother. Other than that, you can't glean much from what you have shared.

[@carmelmiller4165]

This is most interesting to me as I have an 80 cm segment shared by myself, mother and daughter. This is also shared by another lady with no autosomal connection. Where is the best area to look for a common ancestor?

[@FamilyHistoryFanatics]

X-DNA matches without autosomal connection can be several generations removed (in some cases beyong the expected records timeframe)

[@jessikamoore5033]

I have a 20 some cM X match with the exact same mtdna number as mine at 23 and Me but she does not match my Mom's cousins with the same mtdna number, how is that possible?

[@suzannemcclendon]

With all of the recombination going on from generation to generation, is it possible to have absolutely no autosomal DNA from a specific 2nd great-grandparent?

[@FamilyHistoryFanatics]

No autosomal DNA from a 2nd great-grandparent? Yep. That's entirely possible. Which is why you want to test as many descendants of an ancestor as possible.

[@suzannemcclendon]

@@FamilyHistoryFanatics Thank you. I was thinking that it could be possible, but wanted to be sure. I wonder if that is what is at play with my Maggie Robinson Williams, or if perhaps she wasn't really my 2nd great-grandma, but a step-grandma instead. Whatever is the case, still no luck with her. Thanks again. Have a blessed day.

[@seanoxton5572]

I've seen the minimum amount of x chromosome explained in its significance but what about larger matches. I have a second cousin (according to 23 and me) who I have a 175 CM x match. Can anything be inferred by a large continuous segment?

[@FamilyHistoryFanatics]

On X- DNA it is very possible to get large segments with distant relatives.

[@xxk3rd196]

3:17 are you saying “you don’t inherit dna” fully or partially

[@FamilyHistoryFanatics]

Fully.

[@xxk3rd196]

@@FamilyHistoryFanatics thanks. I guess when you see a consistent 1% of a particular community eg. Greece Cypriot or Iranian… would you assume its 1/6 generation ancestors

[@ericpham5198]

Can nitrogen content in the air affect our DNA like Fossil fuel may influent our consciousness greatly?

[@FamilyHistoryFanatics]

As a genetic genealogist, that's not a topic I reflect on.

[@sheppeyescapee]

I'm fascinated by my mothers X chromosomes, On the dna painting on 23andme her maternal one is entirely British & Irish (English Mother) and her paternal x chromosome is mostly Chinese (Mauritian Creole father) I'm intrigued to figure out who the Chinese ancestor is/was and my mum has a bunch of Chinese matches on her paternal X but I don't think any are close enough to be of use.

[@FamilyHistoryFanatics]

That's definitely an interesting case. I would focus on doing autosomal DNA research first to find the clues you need to pair it with XDNA research.

[@sheppeyescapee]

@@FamilyHistoryFanatics Her closest 100% Chinese match autosomally is 35cM and then above that it's all other Indian Ocean Creoles who are part Chinese. The main problem is lack of matches/close matches. We have one Mauritian close match (111cM) on Ancestry but she has 1 adopted grandparent and another whose name changed and nobody knows the previous name. The only shared match is with my mum's grand-niece so doesn't really reveal anything. Trying to persuade them to upload to myheritage which has a larger amount of Indian Ocean creoles to see if we have more shared matches there but they haven't.

[@mamabear52]

Weirdest X match, my aunt shares 18cm on chrom 22 and 95cm on the X with a woman who is perhaps 2 generations different (the match is younger). I know where the X came from, her maternal great-grandmother, so her mom's dad's mom, she was born in the 1850s. I am not sure the transmission of the younger woman because she is adopted, but I know the family line they share, based on triangulation with a couple of dozen other matches.

[@FamilyHistoryFanatics]

With the autosomal match and the known X transmission line of one of the matches, you actually have a descent chance of solving this puzzle.

[@RedRed-uj5ro]

FIBONACCI sequence in the male line.

[@FamilyHistoryFanatics]

Thanks for sharing.

[@gilgamew]

I have 7 cM match on my X-chromosome with two persons (e.g., A anb B), with no autosomal match. But we triangulate! Also, me and person B form another triangulation group with person C - by 7 cM autosomal match without x-dna match. Is this a good clue or not?

[@gilgamew]

Another point is that me and all persons A, B and C share a common ancestral surname (Makarov). But X-chromosome is never transferred from father to son, as surname usually does. This is quite embarrassing

[@lightyagami3492]

@@gilgamew The only conclusion i can come to is that you ALSO have Makarov ancestors on your matralinial line somewhere.

[@FamilyHistoryFanatics]

The amount of shared cMs is rather small. I wouldn't focus on solving this puzzle until I've resolved how all of my autosomal DNA matches relate, isolate the maternal lines and then compare that with the XDNA matches. It's possible that these matches match further back in the generational family tree and autosomal DNA has not been passed to them but XDNA has.

[@thelmahunter4305]

So what happens when you just have a X only

[@FamilyHistoryFanatics]

An X only match would be 3rd cousin or more distant. If they were 2nd cousin or closer, they would share autosomal DNA as well.

[@alanheadrick7997]

I just received a reply to my comment and my comment is gone. So I have an answer to a question I forgot, DOH!

[@FamilyHistoryFanatics]

Weird. Sorry.