The Shared cM Project: Tracking individual contributions

Do you know about Blaine Bettinger’s Shared cM Project?  It’s the crowd-sourced collection of shared centiMorgans (cMs) for the purpose of analyzing the ranges of cMs found at different levels of relationship (full siblings, half 1st cousins, 2nd cousins, etc.)

If you and your known relatives have done your DNA tests at any of the big vendors, you can submit your data here.  Relationship is asked for, but no identifying information (except your email) is needed for submission.

I have been submitting my own DNA data since 2016 — Blaine released the first results in May 2015.   However, so that I won’t skew the results (with duplicate or triplicate submissions), I keep track of my submissions in my own Excel spreadsheet.  A sample of the page I use is below, filtered on just some of the 2C1R relationships I have submitted.  (I have hidden the names of the two testers involved in each relationship.)

Submission_Shared cM Project

Note that the cM range for my submissions of 2nd cousin 1 removed is from 32 cM to 267 cM.  The vast majority of relatives at this level were known beforehand, or otherwise targeted tests.  In the case of the tester who only shares 32 cM, they share that cM with one of 1st cousins.  The rest of us — my siblings and I — and my 1st cousin’s siblings share a much more “typical” amount of DNA with the tester, around 110 – 140 cM.  And since we all match at the full-sibling level, and at the full 1st cousin level, it (so far!) appears that the 32 cM is just due to the randomness of DNA inheritance.

One thing I did in the beginning was submit a relationship for each vendor.  (My father, for example, has tested at 23andMe, FTDNA, and Ancestry, as have I.)  So, originally, I submitted 3 different sets of father/daughter data.  (Obviously, the cM count varied in only minor amounts.)

Since mid-2017, though, I only submit once no matter how many places the two testers have tested at.  (Blaine does ask for the vendor name when you submit.)

In general, I have said no endogamy — but that is based on what I know of the relationship.  Who knows?  With enough research on certain lines, I may find that indeed there was endogamy.

I also, for my own interest, track “expected” DNA shared with actual DNA shared (assuming grandparents and uncles/aunts share an average of 25% with the tester, first cousins share an average of 12.5%, 1st cousins removed (1C1R) 6.25% and 2nd cousins 3.13%.)  It never fails to amaze me how my sister, brother and I have such variations in the amount of cM shared with a given targeted cousin.

How do you track your submissions, if you are submitting to the Shared cM Project?  Are you concerned with not submitting twice — or do you figure it will all average out in the end (certainly a possibility)?

Cite/link to this post: Cathy M. Dempsey, “The Shared cM Project: Tracking individual contributions” Genes and Roots, posted 31 Mar 2019 (https://genesandroots.com : accessed (date)).

 

23andMe Ethnicity Update

If you’ve tested at 23andMe, have you checked out your ethnicity results lately? 

In a recent post[1], Judy Russell mentioned 23andMe’s latest ethnicity update, which somehow I missed completely!

Naturally, I had to go check it out, fearing a bit that my ethnicity percentages might be “messed up”.  Even though I know they are estimates, 23andMe has for some time had the percentages closest to what would be expected by my family narrative.  My dad is “all Irish”; my mom is “half Italian” due to her father being from Italy.  Et cetera, et cetera.

23andme_ethnicity

Very little has changed in my ethnicity percentages.   Here, I’ve noted in an Excel spreadsheet my former ethnicities per 23andMe (as of November 2018) and my current ones as of today when I reviewed the changes.

What is interesting, though, is that they seems to have taken a page from Ancestry’s “genetic communities” playbook, and zeroed in on specific areas in Ireland, Britain and Italy where my ancestors possibly lived in the past 200 years.

Let’s take a look.  We’ll start with Ireland.  On my paper trail, both my dad’s parents have Irish roots.  My paternal grandfather’s family left Ireland, depending on the branch of his tree, around the time of the Famine and shortly after – say, the 1850 to 1865 range.  My great-great grandfather, Patrick Dempsey, reportedly came from Kings County (now Co. Offaly) – per his obituary.  I don’t have more details than that.  His wife Hanora Hurley (or is it Hanora Riordan) – whom he married in the U.S. — may have come from anywhere in southern Ireland.  Best guess is Co. Cork or Co. Limerick.  On my grandfather’s maternal line, her father’s Lamburth ancestors likely came from England, while her mother Eliza (Landrigan) Lamburth came from the town of Garryrickin, Windgap Parish, Co. Kilkenny.[2]

My paternal grandmother’s father came from Athea, Co. Limerick, as did his father, while his mother came from Cooraclare, Co. Clare.  My grandmother’s mother came from Athea, Co. Limerick, as did her father, with her mother coming from Beale, Co. Kerry.[3]

In sum, my Irish heritage on my Nana’s side is from the province of Munster, specifically southwest of Ireland, around the River Shannon, while my Grandpa’s Irish heritage is from the province of Leinster, specifically Co. Kilkenny and Co. Offaly.

And 23andMe’s ethnicity determination – for the moment at least – largely agrees.[4]

23andme_irishethnicity

County Kerry, County Clare, County Limerick and County Kilkenny are all in the top 10.

As far as Great Britain/the U.K. is concerned, I have no idea where my ancestors came from.  My paternal grandfather’s Lamburth line, here in the U.S. since at least 1800, likely came from England but none of us researching this line have yet “crossed the pond”.  My mother’s maternal grandmother’s Wright line has been here in the U.S. since at least 1730 or so; researchers on this line have not yet crossed the pond either.  Here is what 23andMe estimates[5]:

23andme_ukethnicityPerhaps these areas could be clues, but it would be silly to jump ahead of myself and start researching Wrights and Lamburth/Lamberts over in England without knowing more about the family here in the U.S. in the 18th century.  The references to Scotland surprise me a bit, but could be related to the Gaelic / Celtic heritage of my Irish side.

With respect to Italy, my grandfather’s parents came from the province of Marche.  My great-grandfather was from Fano, and my great-grandmother was from Sant’Elpidio a Mare[6].  Some of us in my family have even gone to Marche and met our living cousins – that’s a story for another blog post.

Here is what 23andMe estimates[7]

23andme_marche_ancestryPretty wild, huh?  Marche!!  Still have to take it with a grain of salt – my brother’s estimated places of origin in Italy are completely different from mine – but still, right now, today, it “fits”.

 

 

[1] Judy G. Russell, “And still not soup…,” The Legal Genealogist, posted 27 Jan 2019 (https://www.legalgenealogist.com/blog : accessed 28 Jan 2019).

[2] For sources, see cathymd, “Dempsey Family Tree“, Ancestry.com (https://www.ancestry.com/family-tree/tree/17377380/family : accessed 26 Dec 2018).

[3] Ibid.

[4] 23andMe, Inc., “Cathy, your DNA suggests that 56.8% of your ancestry is British & Irish”, 23andMe.com (https://you.23andme.com/reports/ancestry_composition_hd/british_irish/ : accessed 29 Jan 2019).

[5] 23andMe, Inc., “Cathy, your DNA suggests that 56.8% of your ancestry is British & Irish”, 23andMe.com (https://you.23andme.com/reports/ancestry_composition_hd/british_irish/ : accessed 29 Jan 2019).

[6] For sources, See cathymd, “Serafini_Diamantini1“ tree, Ancestry.com (https://www.ancestry.com/family-tree/tree/19505554/family : accessed 29 Jan 2019).

[7] 23andMe, Inc., “Cathy, your DNA suggests that 12.6% of your ancestry is Italian”, 23andMe.com (https://you.23andme.com/reports/ancestry_composition_hd/italian/ : accessed 29 Jan 2019).