How to get the most out of your DNA test results

Irish Genealogical Research Society

6:45 p.m. Monday 20 November 2017

Helen Roe Theatre, Royal Society of Antiquaries of Ireland, 63 Merrion Square South, Dublin 2

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TBA

Introduction

DNA testing is not a substitute for genealogical research; rather the two approaches help to corroborate each other.

Genealogists compile family histories by matching up three categories of information:

the oral traditions passed down through the generations;
the archival sources used by traditional genealogists; and
the DNA evidence that often reconciles both, but sometimes refutes either or both (NPE).

The boundaries between oral and archival can be blurred:

Is the description of the deceased on a death certificate oral or archival? (Estimated age at death, parents' names, mother's maiden surname, etc.)
Are family letters and diaries oral or archival?
Are published or unpublished family histories oral or archival?

For example, the 1991 Cosgrove-Corry family history by Fr. Peter Ryan et al. suggests that his GGgrandfather Michael Ryan of Gower (TAB 1825) may have been brother of Dan'l Ryan of Glasscloone (TAB 1826). Can DNA add anything to the oral history and the TAB evidence?

Stanford historian Richard White wrote in his family history Remembering Ahanagran: Storytelling in a Family's Past (Cork University Press, 1999, p. 4):

I once thought of my mother's stories as history. I thought memory was history. Then I became a historian, and after many years I have come to realize that only careless historians confuse memory and history. History is the enemy of memory. The two stalk each other across the fields of the past, claiming the same terrain. History forges weapons from what memory has forgotten or suppressed. Few non-historians realize how many scraps a life leaves. These scraps do not necessarily form a story in and of themselves, but they are always calling stories into doubt, always challenging memories, always trailing off into forgotten places.

The emergence of genetic genealogy has turned this two-way struggle between memory and history into a three-way battle.

You can combine your DNA and your known ancestry to help your long-lost cousins to find you and to find your and their long-forgotten ancestors.

What is DNA?

short for deoxyribonucleic acid
made up of chromosomes and mitochondria, each consisting of molecules of four nucleotides named adenine (A), cytosine (C), guanine (G) and thymine (T)
represented by strings of the letters A, C, G and T

Where does our DNA come from?

When a sperm fertilises an egg, each brings DNA, which is replicated in every cell of the resulting person.

	male offspring	female offspring
sperm	Y chromosome	X chromosome
	22 paternal autosomes
egg	X chromosome
	22 maternal autosomes
	mitochondria

autosome is short for autosomal chromosome.

Inheritance paths

Y chromosome: Only males have a Y chromosome.
The Y chromosome comes down the patrilineal line - from father, father's father, father's father's father, etc.
This is the same inheritance path as followed by surnames, grants of arms, peerages, etc.
X chromosome: Males have one X chromosome, females have two.
X DNA may come through any ancestral line that does not contain two consecutive males.
Blaine Bettinger's nice colour-coded blank fan-style pedigree charts show the ancestors from whom men and women can potentially inherit X-DNA.
Autosomes: Exactly 50% of autosomal DNA comes from the father and exactly 50% comes from the mother.
Due to recombination, on average 25% comes from each grandparent, on average 12.5% comes from each greatgrandparent, and so on.
Siblings each inherit 50% of their parents' autosomal DNA, but not the same 50% (except for identical twins).
Similarly, siblings each inherit 50% of their mother's X DNA, but not the same 50% (except for identical twins).
Sisters each inherit 100% of their father's X DNA.
Mitochondria: Everyone has mitochondrial DNA.; Mitochondrial DNA comes down the matrilineal line - from mother, mother's mother, mother's mother's mother, etc.
The surname typically changes with every generation in this line.

This talk will concentrate on autosomal DNA.
Y DNA is also widely used for one name studies or surname projects.
Targeted mitochondrial DNA can be used to solve more specialised problems - e.g. did two women have the same mother?
Targeted X DNA comparisons can also be used to solve more specialised problems - e.g. did two men have the same mother?

The Autosomal DNA and Genetic Genealogy Websites

You must link your DNA match list and your pedigree chart and share them on the three major autosomal DNA comparison websites:

23andMe.com can not currently be recommended for genealogy for several reasons:

it essentially withdrew from the market by showing many, if not all, of its customers the message "We are continuing to modify some aspects of DNA Relatives in preparation for the transition to the new 23andMe experience" from October 2015 until at least May 2017;
it withdrew further from the established market in August 2017 by becoming the first of the large companies to switch to a GSA chip which is not compatible with the current regular GEDmatch upload; and
it appears to have stopped hosting any type of family trees for its DNA customers.

Commercial and Marketing Priorities

The DNA company to which you pay your money and send your sample has a number of priorities, in this order:

separating you from your money;
assigning ethnicity labels to percentages of your DNA; and
sending you elsewhere for help in finding cousins and ancestors.

Before you get your DNA results ...

As soon as you have sent off your DNA sample, prepare to combine your pedigree chart with your DNA results.
Beginners may not be familiar with the term pedigree chart, let alone GEDCOM file.
Examples of pedigree charts: from TNG, Ancestral Quest, AncestryDNA, ancestry.com, FamilyTreeDNA and GEDmatch.
You must use your favourite genealogy software (e.g. Ancestral Quest) to record your ancestors and cousins and prepare your pedigree chart.
Register at GEDmatch.com.
Export a GEDCOM file containing at least the ancestors of each DNA subject for upload to the relevant DNA websites (Ancestry or FamilyTreeDNA and GEDmatch).
For FamilyTreeDNA.com, include in the GEDCOM file any third cousins or closer already at FTDNA and the shared ancestors; FTDNA will use this information to assign other matches to the DNA subject's paternal and maternal sides (example).

Identity v. Anonymity

There is a trade-off between:

increasing your chances of finding long-lost cousins and ancestors (and being found by long-lost cousins); and
maintaining the privacy of your family history research and DNA results.

If you keep your DNA results or known family tree private, then nobody will be able to find you and you will not be able to find any DNA matches.
If you want to be found, then you must let your potential cousins see your DNA results and your known family tree.

Some customers of the DNA companies appear to wish to maintain a certain degree of privacy and anonymity
Others find it paradoxical that those trying to identify their anonymous ancestors can be so concerned about anonymising their own identity.

The Basic Rules

Reveal your birth surname:

Most people inherit DNA with their birth surname, so identify yourself as a minimum by your birth surname with an initial or a title, e.g., P Waldron or Mr Waldron or Miss Durkan.

Reveal the gender of the person who provided the DNA sample:

Valuable additional inferences can potentially be drawn once it is known whether two X chromosomes (female) or one X chromosome and one Y chromosome (male) are potentially available for comparison.
Women do not have Y-DNA and are encouraged to recruit their male relatives to provide Y-DNA, but they must NOT attach a female name to a male DNA sample, as this causes untold confusion.
Be especially careful not to inadvertently link a male's Y-DNA results with a female's autosomal DNA results at FamilyTreeDNA.com where error-checking does not look for this.

Avoid providing irrelevant information:

Your first name, married surname, adopted surname or marital status reveal nothing about your DNA, so you may keep these private if you wish.

Avoid pseudonyms:

They reduce the chances that your matches will bother to look at your family tree, contact you or share the information about your ancestry that they have and that you do not have.

Be consistent and avoid unnecessary confusion:

A real example (further anonymised):

Ancestry username: tara1234
AncestryDNA samples from mother and daughter (per e-mail exchange)
linked to pedigree charts of an aunt and niece
appear to matches as M.R. (managed by tara1234) and D.C. (managed by tara1234)
neither of these are the real initials
mother's GEDmatch alias and e-mail address both begin with Molly
Molly is the dog's name
it took me

300 days after the mother's GEDmatch upload to associate her AncestryDNA and GEDmatch identities
2 days to get her to upload her daughter's data

Keep all your DNA-related correspondence in a single searchable e-mail archive

Use AncestryDNA or Facebook messages only to exchange e-mail addresses.

After you get your DNA results ...

Download your raw data from FTDNA or AncestryDNA and upload to GEDmatch.
If you used the AncestryDNA lab, use the free autosomal transfer to upload the raw data to FTDNA.
Create and upload an updated GEDCOM file with any new close cousins or ancestors that come to light.
Add DNA information to your genealogy database: use an event field or note tag in your database to track people who are in both your database and the DNA databases.

How can we use DNA in genealogy?

Autosomal DNA can distinguish between identical twins and fraternal twins.
Sometimes autosomal DNA comparison can tell us that two individuals are almost certainly full siblings (Group A on the DNA Detectives Autosomal Statistics Chart).
In other cases it may not be clear whether we are looking at full siblings with below-average shared DNA or half-siblings with above average shared DNA.
Sometimes autosomal DNA can tell us that two individuals almost certainly have one of the relationships in Group B (half-siblings, aunt-or-uncle/niece-or-nephew, double first cousin, grandparent/grandchild).
Evidence of age and evidence from the other parts of the DNA (X, Y, mt) can be combined with the autosomal DNA evidence to narrow down the possible relationships.
Occasionally autosomal DNA comparison can tell us that two individuals almost certainly have a Group C relationship (first cousin, etc.).
But generally autosomal DNA comparison can only give us an estimated probability distribution of the possible relationship groups.
Less reputable DNA companies divide match lists into groups with misleadingly precise headings like "3RD COUSIN" and "4TH COUSIN".
Less informed customers may not understand that these headings are not the exact relationship.
The observed range of shared cM for various relationships can also be seen in Blaine Bettinger's Shared cM project and at dnapainter.com.
DNA PAINTER also allows one to keep track of which DNA segments have been traced to which ancestor.

Example

When Thomas Clancy (1919-1989) and Tess Devine (1925-2012) became engaged, they did not know whether they needed a dispensation to marry.
The Devine family had fantastic oral knowledge of family history.
Maureen (1923-2015) was recorded by Cuimhneamh an Chláir.
Three possible relationships:

Tess's paternal grandmother was also a Clancy; Y-DNA comparison between Thomas's 2C1R and Tess's 3C (genetic distance 4/37) has confirmed that their Clancy GGgrandfathers were from the same lineage, but no common ancestor has been identified; certainly no closer than 4th cousins.
Thomas was greatgrandson of Patrick McInerney (d.1899 aged 80) and Tess was GGgranddaughter of Honora Haugh née McInerney (d.1849 aged 40), who were from the same house in Ballard townland and closely related (siblings or aunt/nephew?); if siblings, then bride and groom were 3rd cousins once removed; but ages at death on tombstone inscriptions cast doubt on this theory (only a 13-15 year age gap between mother and daughter).
Another cousin wrote of Thomas's greatgrandmother:
Mary Anne [sic] Keane is most assuredly a daughter of Charles Keane of Baltard. I've never found anything concrete such as a baptismal record, but I have other secondary documents showing her husband Patt McInerney with a Charles Keane (could be the father or son) and now I have several DNA matches with various Blackall descendents.
If this is correct, then Thomas and Tess were also fourth cousins once removed on the Blackall side.

If suitable candidates can be located, mitochondrial DNA or X DNA comparisons might confirm the McInerney and/or Blackall relationships.
With or without DNA, all the relationships are too distant to require a dispensation.

Using the GEDmatch.com tools

'One-to-one' compare

*Molly above and her daughter are at AncestryDNA and eventually copied their results to GEDmatch.

The daughter is an AncestryDNA match to her mother's probable 4th cousin, but the mother is not.

This is one of the few cases where one should reduce the "SNP count minimum" and "Minimum segment cM" size.

What does GEDmatch tell us?

mother v. 4C:

5    91,139 2,575,212 7.5 514
5 2,635,828 4,509,841 5.5 556

dau. v. 4C1R:

5    91,139 2,436,722 6.9 477
5 2,450,617 4,568,447 6.5 616

The breaks are 0.23cM/30SNPs for the mother, but only 0.06cM/3SNPs for the daughter (using Map Interpolator of the Rutgers Map):

half-identical by chance?
two crossovers very close together?
fuzzy boundaries?
misreads?

Is AncestryDNA's failure to identify the 4C relationship a false negative?
Or is the identification of the 4C1R relationship a false positive?

Triangulation

My favourite way to find triangulation groups is via the Tier 1 Matching Segment Search
Use an Excel macro to save the output to a spreadsheet
Example:

There is an X chromosome triangulation involving Thomas (and his daughter), Bernard and *Molly:

X 39,269,992 53,341,687 20.9 1,516 Thomas/Bernard
X 40,677,339 53,341,687 16.5 1,308 *Molly/Thomas
X 40,677,339 71,763,799 24.3 2,318 Bernard/*Molly

Bernard and *Molly are known second cousins and appear to have inherited their shared segment from their greatgrandmother Anne Kitson née McMahon (1872-1944), who was also Thomas's first cousin twice removed, but on his paternal side, from which he did not inherit X DNA.
Anne's mother was a McInerney.
Oral tradition is that Thomas's maternal greatgrandmother Margaret O'Connell née Mahoney of Carrowblough More was related to another Mahoney family living in the adjoining townland of Lismuse (same civil parish [Killard], different Catholic parish [Kilkee/Doonbeg].
There is a tombstone inscription suggesting that her mother was also a McInerney.
So Thomas's parents may have been third cousins.
GEDmatch cannot confirm in either his or his sister's results that they are their own fourth cousins; they have other siblings who have not submitted DNA samples.

Are your parents related?

Paul has a paternal greatgrandmother and maternal greatgreatgrandmother both named Halpin and, as in the McInerney example above, believes that they were from the same house in Drumdigus townland and closely related (sisters or aunt/niece?)
There are direct female line descendants of both Halpin women at AncestryDNA; comparing their mitochondrial DNA at FamilyTreeDNA.com would confirm the precise relationship.
GEDmatch finds these segments which are common to Paul's paternal chromosome 2 and maternal chromosome 2:
```
2  23392137  31463497  8.6 2032
2 125359911 146532207 20.5 4596
```
The Matching Segment Search reveals that Kathleen also shares this segment.
She also has a Halpin greatgreatgrandmother (married before civil registration, no church marriage record found, lived in Kilkee).
So Kathleen now knows that her Halpin ancestors probably also came from the only Halpin family in Drumdigus.

Autosomal matrix

Example
Facebook post
Anne McMahon née McInerney of Baltard (75 in 1901, 80 in 1911) also lived on what had been McInerney land in Baltard in Griffith's Valuation in 1855.
There is a tombstone "Erected by Thos. McInerney, Baltard in memory of his beloved wife Ann McInerney alias Kelly who died May 19th 1856 aged 61 years May she R.I.P. Amen."
Were Patrick, Honora and Anne all children of Thomas McInerney and Ann Kelly?
Did they have a fourth sister Bridget Marrinan née McInerney?

Bridget Marinan was 60 in 1901
She had a child baptised in 1856
Bridget Marrinan was 82 in 1911.
Bridget Marrinan was 85 when she died in 1914 according to her tombstone.
Bridget Marrinan was 95 when she died in 1918 according to her death certificate.
Printed family history says she was from Doonmore, two townlands away from Baltard.
Descendant's user-submitted ancestry.com tree says she was from Baltard, but baptised in Tulla parish!

Ages at death on tombstones imply that Honora was born when her possible mother Ann was only 13-15 years old.
The first six rows in the autosomal matrix represent possible descendants of Ann McInerney née Kelly, and the last four rows represent confirmed descendants of her possible brother Thomas Kelly.
The first two rows are siblings descended from Patrick McInerney
The next two rows are siblings descended from Honora Haugh née McInerney
The fifth row is a descendant of Bridget Marrinan née McInerney
The sixth row is a descendant of Anne McMahon née McInerney
Adding more people to the matrix will allow inferences to be drawn with greater confidence.

Conclusion: Why you should submit your DNA

The value of DNA "testing" to genealogists increases dramatically with the number of people from the relevant geographical area and relevant extended family group already in the DNA databases used.
Submitting your DNA to a database has significant positive externalities for existing and future researchers.
We need to persuade more Irish people to submit DNA samples to the databases for purely genealogical purposes.
Your descendants will be eternally grateful to you for leaving them your DNA.