How to get the most out of your DNA results

1:30 a.m. Tuesday 9 November 2021 (Irish time)/5:30 p.m. Monday 8 November 2021 (Washington time)

by Paddy Waldron

WWW version:

http://pwaldron.info/WSU2021/

YouTube version:

TBA

Outline

Introduction

DNA testing is not a substitute for genealogical research; rather the two approaches help to corroborate each other.
DNA is as much part of finding your roots today as is consulting census returns, and can help to break down brick walls in your research.

Genealogists compile family histories by matching up three categories of information:
  1. the oral traditions passed down through the generations;
  2. the archival sources used by traditional genealogists; and
  3. the DNA evidence that often reconciles both, but sometimes refutes either or both (NPE).
The boundaries between oral and archival can be blurred:
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.

Identity v. Anonymity

The Genetic Information Nondiscrimination Act of 2008 has caused confusion:

The basic rules for genetic genealogy

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 (chromosomally female) or one X chromosome and one Y chromosome (chromosomally male) are potentially available for comparison.
People who are chromosomally female do not have Y-DNA and are encouraged to recruit their chromosomally 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 and aliases:
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):
Keep all your DNA-related correspondence in a single searchable email archive
Use the messaging systems on the DNA wesbites and social media websites only to exchange email addresses.

What is DNA?

Where does our DNA come from?


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

Inheritance paths

Y chromosome
Only males have a Y chromosome.
The Y chromosome comes down the patrilineal line virtually unchanged - 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.

The autosomal DNA comparison websites

You must link your DNA match list and your pedigree chart and share them on the major autosomal DNA comparison websites:
The pedigree chart should include names, dates and places for as many generations of ancestors as possible, say five generations.

23andMe.com is difficult to recommended for genealogy as it is limited to two-generation pedigree charts with places only, but no names or dates!

Websites may accept raw data files:

So the cheapest way to get into the system and fish in all the gene pools is:

You are more likely to find confirmed relatives on the DNA comparison websites:

The DNA Geek provides regular updates on customer numbers.

How can we use autosomal DNA in genealogy?

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:
  1. separating you from your money;
  2. assigning ethnicity labels to percentages of your DNA; and
  3. sending you elsewhere for help in identifying cousins and ancestors.

Combining pedigree charts and DNA results

Add DNA information to your genealogy database:
Add genealogy information to the online DNA databases:

Aggregating autosomal match lists and segment data from the different DNA websites

DNApainter.com is one of several tools for aggregating:

Example DNApainter profile.

A case study: the Lynches of Moveen West

Episode 1

Episode 2

Conclusion: Why you should submit your DNA

Further reading