The following document is sent out regularly on the DNA-NEWBIES mailing list at Yahoo groups. It is is also available as a word or PDF document in that group’s files area.
Feel free to suggest other questions that should be included. Please note all the book recommendations and links to DNA vendors are my affiliate links, a small way to thank me for doing this FAQ.
Table of Contents
It is impossible to discuss genetic genealogy without using terms specific to this field. Kelly Wheaton has put together a wonderful lesson series for newbies that should help you learn the language and more importantly clarify many of the concepts:
More classes and tutorials are listed below, as well as some books.
Is there an acronym or abbreviation list somewhere?
The ISOGG wiki has this list
The DNA Adoption website has this list
The ISOGG wiki has detailed explanations of all these terms.
The DNA adoption website has this glossary
For a more in depth understanding try Kelly Wheaton’s lessons on autosomal DNA
Base Pairs are the physical measurement along a chromosome while centimorgans are a measurement of the frequency of recombination. Centimorgans (cM) are the best measure of the importance of a DNA match, the larger the better. A SNP is a location where there is often a variation in a base pair from the norm, thus it can be useful for ethnicity and matching.
More on this topic here:
Base Pairs: https://en.wikipedia.org/wiki/Base_pair
Since both of these are often used in conjunction with Y testing the simplest way to think of it is that the STR differences occur in the genealogical time frame while the SNP differences on the Y are much older and are used to determine the Y haplogroupings.
A SNP is a “single-nucleotide polymorphism” what that means is a place where DNA might differ between two individuals. Autosomal DNA tests are all about testing the SNPs on the 23 chromosomes where people are most likely to differ from each other.
STR is a change in the number of repeats, mainly used for Y chromosome testing
A good summary of the three types of DNA tests is here:
or read these articles by Cece Moore (old but still very helpful) at geni.com:
Part One, Y-DNA: http://www.geni.com/blog/dna-testing-for-genealogy-getting-started-part-one-375984.html
[Part 4 on ancestry estimates is out of date now]
To learn more about DNA testing look through the materials listed at the ISOGG wiki
This depends on your goals and your budget.
Richard Hill’s e-book can help the absolute newbie make that decision, Guide to DNA Testing: How to Identify Ancestors, Confirm Relationships, and Measure Ethnic Ancestry through DNA Testing – available from Amazon.
ISOGG has a comparison chart of the testing companies here: http://www.isogg.org/wiki/Autosomal_DNA_testing_comparison_chart
Note that the DNA data from an ancestry.com tests and/or 23andme test can be uploaded to Family Tree DNA and MYHeritage for free. At Family Tree DNA you get a limited account that shows your matches shown and their trees with the upgrade to the full set of tools a mere $19. LivingDNA is also taking uploads with results to be ready summer 2018.
This has made most of us genetic genealogists recommend testing at ancestry DNA and then uploading the raw results to Family Tree DNA, Gedmatch, MyHeritage and DNA.land. Do 23andme as well if your budget allows this or if your ancestors are primarily non USA.
My personal thoughts on where to test are as follows. If you are interested the health issues and/or want the best ancestry composition then test at 23andme. Also test there if your ancestors are not American. If you have Jewish ancestry or are testing a very old person start with the family finder test at familytreeDNA.com – it uses a cheek swab, easier for the elderly and preserved the sample so you can use it for other tests. If you are British, Irish, or have colonial ancestry the largest database is at Ancestry.com but they have the fewest tools for comparing DNA. If you are adopted, test at all three companies. Wherever you test, upload your results to GEDmatch.com (or their Beta site GENESIS if you did 23andme) for the best ancestry composition tools and many other great tools as well as to compare with testers from other companies. Uploading your results to DNA.land and MyHeritage.com may also find other matches.
The newest place to test, for those with ancestry from the British Isles looking for a more detailed regional breakdown, is LivingDNA. Hhere is our own Debbie Kennet’s results review with links to many others:
Those results can be uploaded to the GENESIS site at GEDmatch for comparison to other testers.
Note that if you are searching for a specific surname, a Y test at familytreeDNA.com might make the most sense. If your puzzle is on the maternal line then their mtDNA test may be what you want but it has limited use in genealogical time frames. If you are interested in your deep ancestry then either Britain’s DNA or the Genome 2.0 test at National Geographic may have your answers.
Read this for more thoughts on which DNA test to do:
ISOGG has pages on the other tests also:
There are always holiday sales starting at about Thanksgiving for family tree DNA and Ancestry. Family Tree DNA often has sales on the various Y tests around father’s day
ISOGG has a page on shipping DNA kits which includes details of package forwarders that some ISOGG members have used to order a DNA test kit and bypass the country restrictions and/or the excessive courier charges:
As many relatives as you can talk into doing it! Best to get the oldest generation tested now while they are still here and also their genes are closest to your ancestors. But again, it depends on your goals. Personally I have found 2nd cousins to be very useful for isolating matches to a specific family line.
Maybe. Usually you would need the follicle but see Judy Russell’s post on that
The ISOGG wiki has a list of resources for adoptees here
as well as this page of information on how to use DNA
Leah Larkin has done a terrific summary of the process of using DNA for adoption searches on her blog at http://thednageek.com/getting-started-in-an-unknown-parentage-search/
You can go to http://www.dnaadoption.com and learn more about using DNA for adoptees and take online classes.
In addition, there is a DNA group specific to adoptees at http://groups.yahoo.com/neo/groups/dnaadoption/info . Also there is a group of Search Angels willing to help you out with your basic Adoption search. Find out more at http://groups.yahoo.com/neo/groups/SoaringAngels/info
Last but definitely not least, the DNA Detectives Facebook page is a great resource for adoptees and those with unknown parentage. They have had a huge amount of successes and have over 13k members helping each other. https://www.facebook.com/groups/DNADetectives/
If you are a newbie, try this concepts series from the DNA-explained blog
The ISOGG wiki has a long list of excellent genetic genealogy blogs here:
A shorter list with longer descriptions is here:
The Journal of Genetic Genealogy is being published again under the umbrella of ISOGG, special thanks to list member and new editor Leah Larkin,
Family Tree Magazine frequently has DNA articles
The field changes so rapidly that it is hard to recommend books, however there are a few…
If you are totally new to DNA testing try this short e-book to understand the very basics and where to test, Guide to DNA Testing: How to Identify Ancestors, Confirm Relationships, and Measure Ethnic Ancestry through DNA Testing , by Richard Hill, available from Amazon
Genetic Genealogy in Practice by Blaine Bettinger and Debbie Parker Wayne – This workbook includes exercises to test your understanding. Good for all levels from beginner to advanced. A print version is available from the National Genealogical Society. A Kindle version is also available from Amazon.
The Family Tree Guide to DNA Testing and Genetic Genealogy by Blaine Bettinger – very good explanations of all the important concepts and tests.
This book is a great help for those just starting also: Genetic Genealogy: The Basics and Beyond by Emily Aulicino.
A more in depth guide is available from David Dowell, NextGen Genealogy: The DNA Connection
Family Tree Magazine has a number of interesting looking free Ebooks
For a great story of an adoptee using DNA to find biological family read, Finding Family: My Search for Roots and the Secrets in My DNA by Richard Hill (again).
For the exciting and moving story of the famous foundling Paul Fronczak finding his family with the help of Cece and the DNA detectives read The Foundling: The True Story of a Kidnapping, a Family Secret, and My Search for the Real Me
For a detailed story of figuring out relationships in an Ashkenazi family there is a book by Israel Pickholz called Endogamy: One Family, One People
The story of how DNA affected a genealogist and newsman when he learned his Dad was not his biological father – The Stranger in My Genes by Bill Griffeth
DNA Biology Basics, an online course by Dr. Nancy Custer
which includes an excellent desciption of meiosis
A good video on the Basics from Debbie Kennet at the Who Do You Think Your Are? conference Birmingham, England:
“DNA demystified: a beginner’s guide to genetic genealogy”
and a blog post from Jim Bartlett at his blog Segmentology
Good overview of genetics and genealogy by Stephen Morse:
Webinar: Organizing your Genetic Genealogy by Diahan Southard
More from Diahan at her site
Kitty’s basics pages
The National Genealogical Society is now offering an online class in autosomal DNA given by Debbie Parker Wayne: Continuing Genealogical Studies: Genetic Genealogy, Autosomal DNA
A free online course from Kelly Wheaton
The DNA adoption site offers several online classes:
Coursera.org has two free courses on DNA which get technical very quickly but the early lessons may be of use:
and this Utube video with Cece’s presentation
and this update for the nw version of 23andme.com
and some links with more up to date screen shots here:
and some webinars from Family Tree DNA
You can look up the amount you share with a new DNA relative on this calculator:
See this article for the expected percentages:
as well as this study by Blaine Bettinger for the real life numbers:
and this one for the expected number of cMs and segments
Most likely you have more than one common ancestor which makes your relationship look closer than it is. If you come from a very endogenous population such as Ashkenazim or Mennonite then all your relationships will look closer than they are
GEDmatch has a tool for looking at your data to see how likely it is that your parents are related
David Pike has a number of tools also for looking at your raw data
By the way, the abbreviation MRCA is used for “Most Recent Common Ancestor.”
The companies are not always accurate with their predictions and many relationships like a half sibling will look like other relationships. So the DNAadoption folk have come up with a calculator, see
Warning, this work best for closer relationships. When you have just one segment greater than 7 cM for a match it can be anything from a 4th to a 10th cousin and smaller matches than that are most often false.
Kitty did a blog post on that subject:
If you have a tree at ancestry and test DNA there, they do attempt to match you to DNA relatives automatically.
If you have a tree at GENI and you have tested at Family Tree DNA, you can connect your tree to your DNA results.
Family tree DNA will do some tree matching see
With smaller segments it becomes a matter of percentages. Where
IBS = Identical By State = by chance
IBD = Identical By Descent = inherited
(see http://blog.kittycooper.com/2014/10/when-is-a-dna-segment-match-a-real-match-ibd-or-ibs-or-ibc/ for good explanations of these terms)
(per analysis by John Walden)
% IBD one side phased
% IBD both sides phased
% lost by second phasing
An Ashkenazi biologist researcher claims that it is not worth bothering with matches where the largest segment less than 23cM in that population group (but if phased,18cM).
Here is a good write up of why we avoid small segments by list admin Debbie Cruwys on her blog
You can be anywhere from 4th to 14th cousins. See this article
See also the chart in the Wiki based on computer simulations which shows the distribution of segments of different size across the generations:
As you will see, around 10% of 40 cM segments will date back beyond 10 generations.
Maybe. The X chromosome can reach farther back in time than the other autosomes. The approximation I have heard is that the X recombines at about 2/3 the rate of the other chromosomes. Since X chromosome matching was added to Family Tree DNA ,there have been many questions and good blog posts on the subject.
The lists below are taken from Kitty’s post What does shared X DNA really mean?
- ISOGG’s article on the X
- Fan charts of X inheritance by Blaine Bettinger
- Steve Handy’s post on the X
- Debbie Parker Wayne, “X-DNA Inheritance Charts
Triangulation in autosomal DNA analysis is the term for when three people match each other on the same DNA segment of at least 7cM, thus are proven to have a common ancestor.
A further explanation and examples are in this post of Kitty’s
A detailed how to is in this blog post from Jim Bartlett:
The last word and links to many other articles at the ISOGG wiki:
A pile up is where many people all match each other, perhaps 40 or more, and no recent ancestor can be found; it is expected that the ancestor is very far back in time. See this blog post for more:
The key to getting a response is to be specific as possible. For example, “based on your common matches you look to be related on my Gastafson line from Southern Sweden.” By the way, most of us get about a 10%-30% response rate, so do not feel bad at your lack of replies.
Louise Coakley has some helpful templates for contact e-mails:
Someone on the list once posted this terrific introduction he uses in his 23andme intrductions.
“I would like to share genomes at a basic level (no health reporting, only shows where we match on our chromosomes) to see where we overlap and perhaps find our common ancestors.”
Recently Roberta Estes did a good blog post on this subject:
and Amanda Reno of DNA detectives did this video (focus is for adoptees)
Peggy Deras created a nice excel template available in the DNA newbie files area as is a word document on how to use it
Kitty Cooper also has some templates in her downloads area
My ancestry is half XYZ and half ABC yet my ancestry composition is showing only a little of each of those and lots of PQR?
None of the testing companies have completely accurate predictions. 23andme is the best of the lot. All are dependent on who has tested from which countries. If your population group is not well represented then no predictions are going to be all that accurate. Plus there was plenty of population movement hundreds of years back that you may not be aware of.
Read this blog post from Judy Russell on ancestry percentages:
Try uploading your DNA results to GEDmatch.com and using their ancestry composition tools (they call it admix). This presentation demonstrates using the GEDmatch.com admixture tools starting with this slide
About 120 from the last 10-12 generations. See this article for the details
Probably not useful unless all your ancestors are from one country. Read what Debbie Kennett says:
and another more detailed and disappointed blog post from someone who tried it:
GEDmatch.com takes raw DNA data and GEDcom uploads. This lets you compare to testers from other companies as well as do more analysis. Lots of great ancestry tools (admix) among others.
DNA.land is the latest site that takes your DNA and compares it to other testers. The site purpose is for research for a group from Columbia University but they will also give you some matches and ancestry as well.
The ISOGG wiki has pages listing autosomal DNA tools, Y-DNA tools and mtDNA tools:
Autosomal tools: http://www.isogg.org/wiki/Autosomal_DNA_tools
Y DNA tools: http://www.isogg.org/wiki/Y-DNA_tools
mtDNA tools: http://www.isogg.org/wiki/MtDNA_tools
Kelly Wheaton has a good list of tools here:
and the author of this FAQ, Kitty Cooper has a list of her tools and her other favorite tools here: http://blog.kittycooper.com/tools/
ISOGG has an entry with many links about chromosome mapping here: http://www.isogg.org/wiki/Chromosome_mapping
which include links to Tim Jantzen’s methodology
Roberta Estes does a very good job of explaining the chromosome mapping technique in this blog post:
The National Library of Medicine has a chromosome by chromosome resource. Of course most genetic research has concentrated on diseases and problems not traits.
UCSC has a Genome Browser website. This site contains the reference sequence and working draft assemblies for a large collection of genomes. It also provides portals to the ENCODE and Neandertal projects. Located at http://genome.ucsc.edu/
23andme’s one to one comparison does show some traits (under family and friends, gene comparison)
And to learn more about specific genes try SNPedia
Whichever company you used, you can discover what health information lurks in that subset of your DNA which was tested by uploading your raw data to Promethease.com for $5.00. This is by no means definitive and new discoveries are made every day.
23andme does show some of the more well known genetic health issues explained very carefully.
Try this web site on debunking genetic genealogy myths
When you are no longer a newbie feel free to stay and help. However you may pose your more advanced questions on the rootsweb list for DNA and genealogy or the one for autosomal DNA:
If the Big Y is your issue try
There is a standards document published here:
That document is intended to provide ethical and usage standards for the genealogical community to follow when purchasing, recommending, sharing, or writing about the results of DNA testing for ancestry.
The ISOGG Wiki has a page on genetic genealogy courses and conferences:
Every year there is also Genetic Genealogy Ireland which has lectures on their channel at youtube, https://www.youtube.com/channel/UCHnW2NAfPIA2KUipZ_PlUlw
see the report from Debbie
Then there is DNA day at the SCGS Jamboree in Burbank in June
Rootstech in February always has some good genetic genealogy lectures
Here is the livestream of Cece Moore’s keynote speech at Rootstech 2017
Many of the lectures from the Who Do You Think You Are, a conference in the UK every year are available on youtube at
Also many of the lectures from the Genetic Genealogy Ireland conferences are at YouTube as well
DNA is mainstream these days, so most genealogy conferences will have many genetic genealogy talks.