29 October 2013

Learning About Autosomal DNA for Genealogy

CeCe Moore and Shannon Christmas discussed strategies for using autosomal DNA to resolve your genealogical problems on BlogTalk Radio. Part One of this discussion took place on 28 June 2013 and is archived at http://www.blogtalkradio.com/bernicebennett/2013/06/28/strategies-for-using-autosomal-dna. Part Two took place on 28 October 2013 and is archived at http://www.blogtalkradio.com/bernicebennett/2013/10/28/strategies-for-using-autosomal-dna-part-ii.

Some key points made (and paraphrased by me) include:
  • How much time do you have to invest in analysis of distant matches? If time is limited focus first on closer matches (those with the largest shared DNA segments).
  • Don't ignore "low-hanging fruit" such as matches with a common surname or geographic region or shared haplogroup that may match a line you are interested in.
  • If more time is available the more distant matches should also be analyzed. Some of these may not prove fruitful, but some will.
  • AncestryDNA matches through trees can be very useful [DPW comment: assuming the trees are accurate.] AncestryDNA uses mega-base pairs, not centimorgans, as the unit of measurement. See CeCe's blog post, "Ken Chahine Answers My Questions and Reveals Behind-the-Scenes Information about AncestryDNA" for more information.
  • Family Tree DNA requires a total shared number of centimorgans (all segments added together) and at least one segment over the 7.7 centimorgan threshold to be considered a match. Smaller segments must also be indicative of being a part of the same population; this affects African American testers who may have DNA from multiple populations.
  • 23andMe requires 7.0 centimorgans and 500 SNPs to be considered a match. Ancestry Finder reduces the threshold to 5.0 centimorgan segment sizes.
  • Capturing all of your analysis in a spreadsheet is essential. [DPW NOTE: DNA analysis takes time. Be sure you log your findings in some electronic file you find easy to use - spreadsheet, database, word processor file, or whatever. And be ready to invest time if you want to really use the results as evidence.]
  • DNAgedcom.com offers some very useful tools for DNA analysis.
  • DNAadoption.com offers a documented methodology and online classes for atDNA analysis. The same techniques that work for adoptees work for other genealogical brick walls.
  • Any atDNA match sharing more than .40 percent (that is point four percent, which is over 30 centimorgans) is considered a close match.

Many other educational opportunities are also available.

CeCe Moore presented an advanced autosomal DNA analysis webinar for the Association of Professional Genealogists (APG) on 21 September 2013. It hasn't been archived yet, but presumably will be available in the APG Members Only area at some time in the future. The handout for this session is extremely useful.

Roberta Estes presented two DNA webinars for APG that have been archived in the Members Only area. They are:
Part 1: "Intro to DNA" recorded 30 October 2012, and
Part 2: "Yikes, My DNA Results are Back! Now What?" recorded 29 November 2012.

My own sessions available online include:

Khan Academy, Udacity, and Coursera offer online classes in biology and genetics, some free and some with a fee.

Many other educational opportunities are coming soon like a week-long Practical Genetic Genealogy course at the Genealogical Research Institute of Pittsburgh (GRIP) in July 2014, more DNA sessions at the Forensic Genealogy Institute, and many more all-day genetic genealogy offerings which will be highlighted in the future.

To cite this blog post:
Debbie Parker Wayne, "Learning About Autosomal DNA for Genealogy," Deb's Delvings Blog, posted 29 October 2013 (http://debsdelvings.blogspot.com/ : accessed [date]).

© 2013, Debbie Parker Wayne, CG, CGL, All Rights Reserved

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