Lost in X – DNA that is

Despite having other pressing family tasks I’ve found myself lost in DNA results and especially the X chromosome matches. I had my autosomal DNA (aka Family Finder) tested some time ago but have never really come to terms with the matches presented by Family Tree DNA.

I’ve been fortunate lately to find a known second cousin has also been tested, and even better we have loads of DNA in common…well compared to my earlier matches. As we also know our genealogy from traditional methods, it means that we can focus down on where our X chromosomes may have been generated. Interestingly, we both have good overlaps on the X chromosome with a couple of women who only come in at the likely 4th cousin level, Sandra S and Linda S (who also have some reasonable shared Cms with me/us on some of the other 22 chromosomes).

To state what is generally well known, a girl child inherits an X chromosome from her mother and another from her father. The father’s comes down intact exactly as he inherited it from his mother. Any genetic jumbling, aka recombination, happened at his mother’s level ie with the paternal grandmother.

The X chromosome inherited from a girl’s mother will not match the mother’s exactly. Rather it goes through the jumbling or recombination process, amalgamating genetically the two X chromosomes the mum inherited from the female child’s maternal grandparents.

So the X-chromosome Dad gave me is a direct reflection of whatever his mother Catherine passed on to him. This is a genetic blend of the X-DNA from my great-grandmother, Isabella Morrison of Cairndow and Strachur in Argyll, and that of my Sim great-grandparents over in the east of Scotland, in Stirlingshire.

My mother’s X-DNA is a blend of her two X chromosomes, which were inherited from my maternal grandparents ie McSherry and Melvin, so a combination of Irish and Scots genes. A comparison between my mother’s X-DNA and mine will not be identical as it has been jumbled up before being passed on. There should however (I think) be a fair degree of overlap. This will become more clear (I hope!) to me when my mum’s results come back.

Follow the pretty pink lines for X-DNA.

Follow the pretty pink lines for X-DNA. While I haven’t filled in all the info I have, the question marks make it clear how many stumbling blocks are thrown up by Irish ancestry.

The chart here shows the pink boxes which generate our X chromosome material. As it cannot be passed on from fathers to their sons, we can eliminate whole sections of a genealogical chart when looking at X-DNA. As the Family Finder autosomal matches predict likely relationships, I found it helpful to illustrate which segments would apply to 2nd, 3rd or 4th cousins. I also noted which countries and known counties or regions my ancestors came from. I haven’t filled in every box but I’m sure you’ll get the drift. It does look like a bit of schmozzle, but what you’re looking for is the pink lines of descent, henceforth known as the “women in pink” and don’t forget you can click to enlarge it. (I acknowledge with thanks the work of Blaine Bettinger, the Genetic Genealogist, in providing us with this tool).

The X chromosome is one of the 23 DNA pairs which make up our genetic being and it is the one which determines our gender (boys only inherit one X and their father’s Y). It is tested as part of the FamilyTreeDNA Family Finder, or autosomal, DNA test. 22 of the pairs are a random mix of all the DNA which is passed on from generation to generation, making it possible to find relations via significant shared SNPs of shared chromosomes.

The X chromosome behaves somewhat differently from the other 22 autosomal pairs. This is partly because of recombination, though some researchers have found that it’s been passed down virtually unchanged over several generations. Even siblings will not necessarily have identical X-DNA for these reasons. I am happy to take the word of the experts that this little gene is rather tricky and not as predictable certainly as Y-DNA or matrilineal DNA.

The X chromosome is not to be confused with matrilineal DNA (mtDNA) which is passed virtually intact from generation to generation down through the mother-to-daughter-to-daughter line. In this case I can expect my mtDNA to have come down through the generations from my 2xgreat grandmother, Mary Camp from Hertforshire, and the women back in line from her.  While my father inherited his mother’s mtDNA he cannot pass it on to me…that’s a genetic “dead end” for me, which can only be tested via Dad’s maternal aunts (now all deceased) or their daughters.

A selection of women who share X matches with me.

A selection of women who share X matches with me. The one in orange is a 2nd cousin.

It seems logical to me (but am I right?) that if an autosomal DNA match includes a match to me on the X chromosome, this might be the best line of research to approach first, especially for those high in my overall matches and relationships. After all, the X-DNA has narrowed down my possible lines of ancestry with its focus on the “women in pink” (see chart). While I have over 400 DNA matches with Family Tree DNA, sharing a range of Cm from 378.4 to say 25, I have only 90 X-DNA matches among these. Some have trees listed, others have names and places (as I do), and some have nothing.

Among my matches I have five probable 2nd to 4th cousins and 25 x 3rd to 5th. While a fourth cousin may seem some distance away, that fades when I realise how much conventional research I’ve achieved through my 3rd cousin once removed in the O’Brien line. This includes providing me with mtDNA which will go back to my 3xgreat grandmother, Catherine O’Brien nee Reddan from Co Clare, Ireland, and generations of women beyond her.

I have had two good autosomal matches in my list for a while and have recently been in contact with the person who manages them. We share no X-DNA but we do have one narrow area of Ireland in common. Of course the problems with Irish documentary research make it difficult to go multiple generations without a fair amount of the luck of the Irish.

I’m by no means confident I’m correct on all these facts and happy to receive advice from more experienced readers –this is by way of “thinking out loud”. It all no sooner seems to make sense than I find myself in another spider’s web of confusion. Many’s the time I’ve wondered what happened to those five years of science I did at school and university.

In trying to get my head around these issues I’ve been assisted by the following blog posts as well as conference presentations by Kerry Farmer and advice from Helen Smith. In each of these posts there are onward links which are worth following. Any false deductions and reporting are entirely my own fault, not theirs. As I said, I’m thinking out loud here trying to sort out my own ideas, so feel free to weigh in with corrections.

DNA eXplained – Genetic Genealogy, Roberta Estes, on X Marks the Spot. (do read the comments as well) and That unruly X – chromosome that is.

The Legal Genealogist, Judy G Russell, on X marks the spot, Whence the X, and Looking at Recombination.

Genetic Genealogist, Blaine Bettinger, on Unlocking the Secret of the X chromosome and also More X Chromosome Charts. The image of the chart of X chromosome inheritance also comes from Blaine and I acknowledge, with thanks, that he has provided this for us to use.

The Lineal Arboretum, Jim Owston, in Phasing the X chromosome (in relation to male inheritance)

Lost in DNA

Lost in a world of DNA.

This week I’ve finally looked at my Family Finder (autosomal) DNA results from Family Tree DNA. I’m a genetic novice so I’m in a state of complete confusion wishing I’d paid more attention previously. You wouldn’t think I’d ever done science as I sit bewildered by it all.

WHY FAMILY FINDER?

Y-DNA is out because my father is deceased, I have no brothers and neither did he. I could go wider to cousins but I “know” my ancestral paternal line from documentary evidence – always assuming no surprises like adoptions/playing away etc.  I’d still like to have a couple of cousins for genetic comparisons on this line but I have no first cousins on this line at all

Matrilineal DNA (MtDNA) and X-DNA are also less of an issue because I again “know” what my line is, even though there’s more work to be done the conventional way. I do have a few first cousins on this line though two of them I haven’t seen since I was about 10. My only uncle on this line had no children…another brick wall on the Y-DNA chart.

Autosomal DNA seemed to be the best strategy for me, enabling me to look at my other 22 chromosomes and their genetic matches.

WHAT WAS I HOPING FOR?

Like anyone (pretty much) with Irish ancestry I hit a brick wall around the time of the Famine, with the limited availability of records. There are also a number of lines for which I only have parents’ names (from shipping lists) and a few where I have nothing before them. These are all at the 6th or 7th generation level, which would bring in 4th or 5th cousins – this seemed just right for the Family Finder DNA test.

MY WISH LIST WAS:

  1. To link with someone who has Sherry DNA from Ireland (I have nothing pre-1860).
  2. To perhaps find descendants of Philip Joseph Kunkel (my 2xgreat uncle)
  3. To learn whether my Furlongs in Tullamore are genetically linked to the Wexford family
  4. To see if I got any new “hits” on my Partridge line enabling it go back further.
  5. Any other connections that arose.

WHAT DID I GET?

As anticipated, no 1st or 2nd cousins, as yet anyway. I suspect there’s some bias in the database in that more Americans are being tested overall (well there are more of them than Aussies anyway). Many of those tested seem to have long lines in the US, making close relationships unlikely….I hadn’t anticipated this, logical though it is.

FTDNA did find three matches at the 3rd cousin level. That’s pretty close as we should share a genetic link at the 2 x great grandparent level. My best link is to someone simply listed as “F” with no further details. We have the greatest overlap of 60.29 cM and a longest block of 32.09. How frustrating not to be able to contact them.

I’ve contacted the other two 3rd cousins and they have replied but so far there’s nary a suggestion of a family link in their tree that I can determine. Can you tell the why I’m getting confused?

I got a fair number of 4th cousins and have contacted some of them. Initially the e-book by the Genetic Genealogist suggests that at this level, the DNA overlap could be coincidental (IBS –Identical by State) rather than due to biological inheritance (IBD or identical by descent). At this point I went back to focus on my 3rd cousins. However FTDNA’s FAQs suggest that their statistical modelling ensures matches are IDB not IDS (FAQ 12). So that makes both 4th and 5th cousins worth investigating in more detail.

ANY SURPRISES?

Firstly I thought I was going to have a pretty DNA image to play with…should have read the manual first.  However I’ve downloaded the raw data which as yet is purely Double Dutch, as they say.

My pie chart for documented ancestral birth places.

I also used the Population Finder tool and got something of a surprise. I expected all of mine to be in the Western European category. To a large extent this was correct BUT I also got another 4.43±1.52% from the Middle East.  This percentage compares very closely to my German ancestry which suggests to me that it’s this line which originates in the Middle East. This was a surprise as this is one of my longest lines which I can trace back to Bavaria in the early 1600s.

My population finder map from Family Tree DNA.

WHERE TO FROM HERE?

As well as the list of 4th cousins, I also have a whole gaggle load of 5th cousins who I will need to investigate further. Some people have email contacts and some also have surnames of interest and GEDCOMs uploaded. I’ll work through those first.

I’ve had a play with the chromosome browser and put my closest/best matches onto that. Of course the elusive “F” reveals a good block of common DNA! I can only hope they come looking for me.

QUESTIONS:

Does anyone know if the Population Finder map will show highlighted areas in continental Europe or always just the UK?

Has anyone used GEDmatch for further comparisons? If so what were your experiences?

 SUMMARY

So there it is, my first foray into the world of genetic genealogy! I feel rather as if I’m in the deep end with my nose barely above the water line while I should be in the toddler pool. There’s much to learn and I’ve been very grateful for Kerry Farmer’s Unlock the Past book on DNA for Genealogists. Seems like I have a lot more reading to do so I can understand this better. My reading will include a number of my Genimates who have written about this topic. Now I have my results, I’ll be more able to see how they can help me with ideas etc.

 Have I misunderstood anything/made a mistake in the process here? Please jump in and let me know. Also feel free to share your experiences with autosomal DNA.