A friend who is also a client was asked some questions about DNA by her friend. She referred that friend to me who didn’t have time for a telephone conversation for a brief consult as we had mutually conflicting schedules. She asked for a simple email to help her make some decisions. Well, that’s not so easy when her motivations to test are unknown and there is simply so much to discuss! Which test; which company; what results can be expected. I had to approach my response blind. No problem! Below is the text of the note I sent her. It may contain a few errors here and there but I don’t believe there is any misinformation.
Any thoughts on what else I should have included?
The first point I’d like to make is that in general, DNA testing does not replace basic genealogical research. Other than an adoptee tracing parents or the parents of an adopted ancestor, that rule would apply. The testing can prove or disprove your research but doesn’t generally do the research for you.
So the question I ask anyone contemplating a DNA test is the motive. In other words, what are you trying to find out? That will help determine which company and which test. What follows is a “brief” discussion that hopefully will help.
There are essentially 3 types of DNA tests:
- Autosomal or atDNA examines 22 of the 23 chromosomes in the nucleus. It is often referred to as “Cousin Finder” or “Family Finder.” These are the pairs of chromosomes that form the familiar “double helix” which are comprised of approximately 50% from each of the parents. Because of this ratio and the fact that is never exactly 50%, any individual will have roughly 25% of each grandparent (4 individuals), 12.5% of each great-grandparent (8 individuals), 6.25% of each 2nd great grandparent (16 individuals), 3.13% of each 3rd great-grandparents (32 individuals) and so on, melting by half as you go back each generation. Because the percentages are never perfect and get quite small at the 6th or 7th generation and beyond, it is possible that an individual may have none of a 3rd or 4th great grandparent’s DNA and thus making a match difficult if not impossible the farther back you go. All the current DNA testing companies do this test with AncestryDNA, 23andMe, and MyHeritage doing atDNA exclusively.
- Y-DNA examines the 23rd chromosome in the nucleus. That chromosome can be a combination of the X from the mother (as females do not carry a Y, otherwise they’d be male) and an X from the father (X/X) or the X from the mother and a Y from the father (X/Y). If the 23rd chromosome is an X/X, the result is a female. If that chromosome is and X/Y, the result is a male. Since the Y comes exclusively from the father and mutates very slowly, it is the Y chromosome that can be very useful in tracing paternal lines. Barring an adoption or “non-paternal events,” it can be a matter of following a line by way of the surname.
- Mitochondrial or mtDNA is the found inside each cell but outside the nucleus. Rather than a linear double-helix configuration, mtDNA is circular. It is transferred exclusively by the female to all her children. Everyone has it but the way it is transmitted, mtDNA will follow the maternal line.
FamilyTreeDNA and LivingDNA currently do all types of testing. FamilyTreeDNA has been testing DNA for longer than the other services while LivingDNA is, perhaps, the latest to enter the market. FamilyTreeDNA has a wide variety of combinations of tests with a variety of prices. LivingDNA, a British company, does one level of test by testing all types of DNA. They call atDNA “Familyline,” Y-DNA “Fatherline,” and mtDNA “Motherline.”
Will the results of atDNA testing be the same at all companies? Not necessarily as they all have developed different their own unique databases but there is a great deal of overlap from one company to the other. Should you test at more than one company? That all depends on your motivation for testing.
Here are the websites and there are many sales running this holiday season between all these very competitive companies:
Some companies accept the “raw data” from other companies. For example, you can upload a raw data file of your results from 23andMe to MyHeritage. The only 2 that I know of that do not accept an upload are AncestryDNA and LivingDNA. There are also websites where you can upload your raw data in order to broaden your ability to compare your results to the results of other testers. GedMatch is one such company. They can be found at www.gedmatch.com.
Blogs to which you can subscribe:
www.legalgenealogist.com by Judy G. Russell who blogs on DNA at least once a week.
www.dna-explained.com by Roberta Estes. Roberta can get a bit overwhelming but still worth a look.
www.thegeneticgenealogist.com by Blaine Bettinger, a nationally renowned expert.
www.yourgeneticgenealogist.com by CeCe Moore who has done analyses for “Who Do You Think You Are” as well as other programs.
Facebook has dozens of pages where you can read the questions and answers that others have posted or join and post your own questions. If you go to Facebook (where there are more than 14,000 genealogically oriented pages), search for ISOGG, the International Society of Genetic Genealogists; DNA Detectives; GEDmatch.com User Group: and many, many others.
The website www.familytreewebinars.com offers webinars on a weekly basis, often on DNA as a subject. Anyone can register for and view current programs. The site has a tab for “Upcoming Webinars” where you can keep an eye out for DNA related programs and register to view. These webinars are open to the public on the day of the broadcast and remain open for about a week or 10 days. Membership is very reasonable and allows full access to their entire 600+ webinars on a broad spectrum of subjects beyond DNA.
There is a great deal more to the subject such as the concept of “Haplogroups,” genetic distances, chromosome browsers and so on. But this should be enough to digest for now.
I hope this helps without confusing the issue.