The following is a guest post by Ann Turner, founder of the of the GENEALOGY-DNA mailing list at RootsWeb and co-author (with Megan Smolenyak) of “Trace Your Roots with DNA: Using Genetic Tests to Explore Your Family Tree.” Thank you Ann for this terrific post!
Genetic genealogists use autosomal DNA testing to locate people who share some DNA, enough to point to a relationship in a genealogical time frame. We’re not impressed by accidental matches that occur simply because all humans share 99.9% of their DNA. We want to be confident that the shared DNA segment is Identical by Descent (IBD) from a particular common ancestor, one who lived some number of generations in the past.
Two practical difficulties stand in the way of definitive confirmation. One is that our pedigrees are not complete, and we cannot test every link in the chain to prove that the segment traveled down the pathway we’ve identified through the paper trail. Indeed, as more data accumulates we frequently discover that a match we attributed to one ancestor must have come through an entirely different line.
[Read on to learn how you could win THREE hours of FREE consultation and research from me for registering in this course before March 21st!]
For the next two Saturdays, March 21st and 28th, I will be spending some quality time with genetic genealogists! My new course entitled “(Finally!) Understanding Autosomal DNA” is a four session course designed to educate genealogists on all the ins and outs of autosomal DNA.
The course is being offered through the wonderful new Virtual Institute of Genealogical Research. The Virtual Institute offers courses on a wide variety of genealogical subjects, providing vigorous year-round education for the genealogical community using a virtual platform.
The four courses will provide attendees with the fundamentals of autosomal DNA, third-party tools, and triangulation. Here is the course schedule (all times U.S. Eastern):
21 March 2015
11:00am – “Introduction to Autosomal DNA”: Learn the fundamentals of autosomal DNA and compare company offerings.
1:00pm – “Using Third-Party Tools”: Free tools offer powerful additional analysis of autosomal DNA test results.
EDIT (3/31/2015) – Beginning on April 1, 2015, I will no longer be able to accept submissions other than through the portal. My sincerest apologies, and I so greatly appreciate the files that have been submitted this way, but I have been inundated and won’t be able to take the extra time to process any non-portal submissions made after April 1, 2015. Thank you!
I need your help! I’m trying to gather data about the ranges of DNA shared by known relatives. How much DNA do you share with your sister? your brother? your second cousin? While it is possible to predict approximately how much DNA you share with a close relative, the actual numbers vary more than you might think.
If you’re interested in participating in this project, I’m looking for two numbers for the known relationship: (1) the total amount of shared DNA in cMs; and (2) the largest shared block in cMs. At Family Tree DNA, for example, you can find the numbers here:
With a database of over 700,000 genotyped members, AncestryDNA has generated over one billion cousin connections to date. In 2015, we project this database to grow to exceed well over one million genotyped members, resulting in even more and higher quality cousin matches.
Following the successful launch of AncestryDNA in the UK, we will soon be bringing the service to our members in Australia and Canada, and in doing so, will connect the major English-speaking migrations and globally connect families like never before.
Building on DNA Circles, in 2015 we will launch a new experience that will use the latest genetic technology to discover new ancestors without the customer having to search records or build a family tree. This new feature will transform how family history research is done by providing valuable hints to help experienced genealogist looking to break through brick walls, as well as open family history to a whole new segment of the population. Through this new experience, AncestryDNA customers will be able to discover new ancestors as far back as the 1700’s by connecting into existing DNA Circles.
DNA Circles Without Family Trees
On the last point, in the coming weeks AncestryDNA will launch an extension of the DNA Circles tool in which they assign you to a DNA Circle without having a family tree connection.
Currently, you must have a decent public tree in order to be put into a DNA Circle based on genealogical relationships. Using this new tool, however, you will (potentially) be put into circles without a tree showing that you belong to the circle (in other words, based only on genetic relationships regardless of the trees).
Many genetic genealogists, myself included, often talk about DNA segments getting “broken up” or “broken down” as they are passed from one generation to the next. But this language can be misleading, since DNA isn’t really “broken up” into pieces when it passed down; instead, a few pieces are traded between nonsister chromosomes in a process called RECOMBINATION.
Genetic recombination is a process of crossover between chromosomes during MEIOSIS (meiosis = a very specialized cell division that creates eggs and sperm for reproduction). Very early in meiosis, the cells duplicate the chromosomes. Normally, every cell has 23 pairs of chromosomes, for a total of 46 chromosomes. However, in the first step of meiosis, the chromosomes are duplicated to result in a total of 92 chromosomes. There are 4 copies of chromosome 1 (2 copies of the chromosome you got from your mother, and 2 copies of the chromosome you got from your father). There are 4 copies of chromosome 2, and so on.
There will be lots more to come, including guidelines for Y-DNA and mtDNA testing and interpretation, as well as some guidance for citing DNA test results in reports, scholarship, and in general. Stay Tuned!
Inspired by other end-of-year posts by Denise Levenick, Judy Russell,Roberta Estes, and others, here are my Top Five Posts in 2014. This year was a turning point for genetic genealogy as it finally switched from a cottage industry to a widely accepted commercial enterprise. I can only imagine what 2015 will bring.
Here are the top 5 visited posts, ranked from highest to lowest:
In my last post (see “Recreating a Grandmother’s Genome – Part 1”), I introduced my grandmother Jane, who died when I was just 8 years old. Although I have only a few memories of my grandmother, I have 25% of her DNA. To explore this rich genetic legacy, I’m trying to recreate as much of my grandmother’s genome as possible using the GEDmatch Tier 1 tool called “Lazarus.”
In the last post we also learned about the new Lazarus tool. In today’s post, we’ll choose what kits to use for my grandmother’s Lazarus kit.
Finding DNA Kits for Lazarus
GROUP 1 – DESCENDANTS ONLY
So GROUP 1 must be descendants of the target Lazarus kit. My grandmother has six children, twelve grandchildren, and eleven great-granchildren. Any of these 29 people are candidates for GROUP 1. Of those 29 people, I’ve tested four of the six children and one of the grandchildren (myself). Yeah, I know, I have more testing to do!
My grandmother Jane died in 1984 when I was just 8 years old. I have some really great memories of her, faded with time but still filled with emotion. Bath times, spending time with her in the summer, newspaper hats, chrysanthemums.
However, in addition to those memories, she gave me a very unique genetic heritage. She was from a region of the world with a high degree of admixture, and thus it is from her that I obtained my Native American mtDNA, my Native American, African American, and Spanish autosomal DNA. It is an incredibly rich and fascinating genetic legacy.
In an attempt to learn more about my grandmother’s genetic heritage, I’m using GEDmatch’s new Lazarus tool to try to recreate as much of her genome as possible. Join me on the journey, and learn about this new tool.