Tracing the X chromosome

[Angela]

For anyone who has tried chasing the matches on the X chromosome, how likely do you think it is that a .71% match on the X is within a relatively recent genealogical time frame?

I ask because I have a match like that with someone of predominately German ancestry, plus some British Isles and I can see no way we have a genealogical connection. Yet, that large a match on the autosomes would indicate a very close relationship.

[Twilight]

For anyone who has tried chasing the matches on the X chromosome, how likely do you think it is that a .71% match on the X is within a relatively recent genealogical time frame?

I ask because I have a match like that with someone of predominately German ancestry, plus some British Isles and I can see no way we have a genealogical connection. Yet, that large a match on the autosomes would indicate a very close relationship.

Hey Angela, how far back in time can you trace your mother's mother's mother's mother's...... side? It's hard to say with the X chromozone how old the connection is; I got .3% West African on my X-Chromozone according to 23andme. So my educated guess is that your connection could be early 19th century or earlier.

[Jovialis]

Hey Angela, how far back in time can you trace your mother's mother's mother's mother's...... side? It's hard to say with the X chromozone how old the connection is; I got .3% West African on my X-Chromozone according to 23andme. So my educated guess is that your connection could be early 19th century or earlier.

About seven generations ago.

Average generation is 22 to 32 years. This would have been consistent with Western European marriage patterns.

154-224 years ago

Between 1793-1863

edit: Maybe that person has a northern Italian great-great-great-great-great-grand mother.

[Sennevini]

X-chromosomes inherit in a choppy way, the father just gives his mother's one to his daughter unchanged, the mother generally gives through a blend of her father's and mother's, however, there are quite some cases in which mothers too give just one of theirs unchanged. I would say because there seem to be fewer reorganizations with the X-chromosome than with the normal autosomes, it could be further back in time than you think.

[Angela]

X-chromosomes inherit in a choppy way, the father just gives his mother's one to his daughter unchanged, the mother generally gives through a blend of her father's and mother's, however, there are quite some cases in which mothers too give just one of theirs unchanged. I would say because there seem to be fewer reorganizations with the X-chromosome than with the normal autosomes, it could be further back in time than you think.

I think it's probably less likely it's from my father's side if it's within the last two hundred or so years, i.e. my paternal grandmother's side, as that side is from a very isolated and remote mountain area. They didn't have actual roads up there until the early 20th century. Plus, my family tree goes back to the mid 1500's and earlier for that part of my family. There weren't any Germans moving in and marrying into my direct line.

On my mother's side I do have a few lines that are vague, but most of them can be traced to the mid-1500's as well.

Perhaps it's on her side and she's just unaware of it, as Jovialis said.

Still, you must be right and the inferences are different for the X than for the autosomes, because .71 would be a very close cousin indeed in the latter case, and you'd probably know about the relationship unless you were adopted or something.

Thanks for the help, everybody.

[Moi-même]

I have unexplained X-match with English-German, too. I am wondering whether the X DNA is less diverse than the rest of the genome, leading to more false positive.

My tree is full up to the 9th generation and quite complete up to the 12th.

[Angela]

I have unexplained X-match with English-German, too. I am wondering whether the X DNA is less diverse than the rest of the genome, leading to more false positive.

My tree is full up to the 9th generation and quite complete up to the 12th.

Glad to know I'm not the only one then. :)

The odd thing is that it's not a combination of smaller chunks, but one solid one, which I think in the regular autosome analysis makes it more likely it's genealogical, and not a false positive.

[Twilight]

I have unexplained X-match with English-German, too. I am wondering whether the X DNA is less diverse than the rest of the genome, leading to more false positive.

My tree is full up to the 9th generation and quite complete up to the 12th.

Actually I've been noticing some German ancestors; and Italian Ancestors also sprinkled into my French Canadian family tree; dated to around the 17th century. Your German-like Mtdna might be legit. :) Since I have no West African myself if Modern German ancestry is not the case then it might be that your German-like Mtdna could be the result of Germanic tribes flooding into France.

[Moi-même]

Angela, there's always a possibility of unrecorded adoption, but since your parents and their family were both in Italy, I would guess a cousin from the same area moved to America or Germany earlier. Or one German moved to America while a brother or cousin moved to Italy. There's also the possibility your match is mistaken with some of their lines as they didn't review the documents properly. There's also the possibility of founder effect in two different villages, one German and one Italian from two brothers (or sets of many siblings) who were quite productive and had equally productive descendants.

The good thing is you are X-DNA match so it rules out a lot of lines. I would check where in Germany his ancestors lived and where in Italy yours lived. If you can't find a regional link, there is probably a papertrail mistake on your match's part.

Twiling, I do have an Austrian guy and a Flemish one, but they aren't on my X-DNA lines. I don't have Italians, but I have a Portuguese, also not in the X-DNA lines. I would guess an older population movement between North Germany and North France, as I have plenty of ancestors from Normandie and Picardie. As for my mt-line, it comes from the Isle of Barra, Outer Hebrides. I feel quite lonely as H2a1 in the Scottish Project, even more so in the French ones. Since the Outer Hebrides were under Norse rule from 9th to 12th centuries, it could be Norse settlers mt-DNA signature.

[Angela]

Angela, there's always a possibility of unrecorded adoption, but since your parents and their family were both in Italy, I would guess a cousin from the same area moved to America or Germany earlier. Or one German moved to America while a brother or cousin moved to Italy. There's also the possibility your match is mistaken with some of their lines as they didn't review the documents properly. There's also the possibility of founder effect in two different villages, one German and one Italian from two brothers (or sets of many siblings) who were quite productive and had equally productive descendants.

The good thing is you are X-DNA match so it rules out a lot of lines. I would check where in Germany his ancestors lived and where in Italy yours lived. If you can't find a regional link, there is probably a papertrail mistake on your match's part.

Twiling, I do have an Austrian guy and a Flemish one, but they aren't on my X-DNA lines. I don't have Italians, but I have a Portuguese, also not in the X-DNA lines. I would guess an older population movement between North Germany and North France, as I have plenty of ancestors from Normandie and Picardie. As for my mt-line, it comes from the Isle of Barra, Outer Hebrides. I feel quite lonely as H2a1 in the Scottish Project, even more so in the French ones. Since the Outer Hebrides were under Norse rule from 9th to 12th centuries, it could be Norse settlers mt-DNA signature.

Mine I know quite precisely. She doesn't know much about hers, so something went into her tree of which she's unaware.