Saturday, March 21, 2009

Genetic genealogy and a glimmer of hope for offspring

In my genealogy class, one of our assignments is to create two brochures on genealogy topics of our choice to teach the class about these resources.  The two topics I chose were Ellis Island (because my great-grandparents arrived there in 1909 and 1912) and Genetic Genealogy (because of course I'm a genetics nerd, so I had to throw a plug to my favorite subject!).  

So anyways, this afternoon I've been working on the Genetic Genealogy brochure and I thought that in the past there's been a bit of discussion about the pros and cons of genealogical DNA tests for donor conceived adults, but I have not discussed the topic in-depth, until now!

Genealogical DNA tests provide unique insight into an individual's recent ancestors as well as historical origins.  These tests do not give medical information.  They are meant to find ancestral links to living relatives.  There are two main types of genealogical DNA tests: Y-STR tests and mtDNA tests.  Y-STR tests trace the paternal lineage, while mtDNA tests trace maternal line

Therefore, Y-STR tests are ideal for MALE donor offspring to gain information about their biological father's heritage, and even find possible surnames.  If anything, a male offspring may be able to connect with genetic cousins, even if he is unable to trace his father.

Females, however, are up a creek without a paddle in terms of tracing their paternal side without a male paternal relative - if you have a brother who's from the same donor that's the only way.  Sorry gals........

So back to Y-STR tests...

Most testing companies offer several different levels of tests, based on how many STR markers they look at: 12, 25, 37, and 67.  The 12-marker test will not offer much information at all, other than possibly what ethnicity you might be.  The 25 and/or 37-marker test (depending on the company) is the best bet, because it gives enough information to find a potential surname and match to other relatives in the database, but it leaves room for a larger array of potential.  Since we are starting with a blank slate in terms of knowledge of paternity, the 67-marker test may be too confined to actually make a match.  

For more information about what STRs are, and how they trace your ancestry, please refer to my post "Whatcha gonna do with all that junk, all that junk in you...DNA?" for a more in-depth explanation.

There are some problems with using this type of test to determine paternity, or even surnames.  Because of secret adoptions (or even donor conception!), infidelity, and random mutations in the past, it's possible that the surname that the test tells you is your ancestral surname, may not be the surname of your biological father.  

So, genetic genealogy tests are a fantastic resource for male offspring, but must be used with caution.  Take the results with a grain of salt.  If anything, think of it as a way to learn about your biological father's ancestors and his history - even if it turns out to not direct you towards him.  

In conclusion, I will leave you with some of the benefits of genetic genealogy.  The decision is yours whether or not you wish to enter into this area in your search.

Some cool things that can be discovered in these tests are:
  • Discovering living relatives
  • Surname/clan reconstruction
  • Identifying ethnic group memberships
  • Determining ancestral homelands
  • Identifying Cohanim ancestry (Y-chromosomal Aaron) - Jewish priests and ancestors of Biblical Aaron (brother of Moses) [Cohen Modal Haplotype]
  • Identifying Native American ancestry
  • Identifying tribal groups 
Caucasian -
Eastern European (Slavic speaking of E. Europe)
Finno-Ugrian (Uralic speaking of NE Europe)
Mediterranean (Romance speaking of SW Europe)
Northwest European (Celtic and Germanic speaking of NW Europe)
Near Eastern:
North African (Sahara Dessert and Atlas Mts)
Mesopotamian (Iran, Iraq)
Aegean (Anatolia: Sicily, Greece, Turkey, Armenia)
Levantine (Semitic: Israel)
Asian - 
Central and South Asian (Indian)
East Asian (Chinese, Japanese)
Sub-Saharan Africa - 
South, East, and West Africa
American Indian - 
Native North American:
Arctic, Mexican, Great Plains, Northeastern, Pacific Northwest
Native Central and South American:
Amazonian, Andean, Central, Mayan, Patagonian
Pacific Islanders - 
Polynesian, Aboriginal

Genetic Genealogy Testing Companies:

23andMe ( - also does medical testing, in case you're worried!
DNA Tribes ( - does not do Y-STR tests but autosomal tribal tests

Results from any of these companies can be uploaded onto the Y-Search public database, which allows individuals who got their Y-DNA test done at any company to compare their results and find relatives! 

Any test that is AUTOSOMAL both males AND females can do, and can give some insight into heritage for the paternal side.

1 comment:

damianhadams said...

Hi Lindsay
I was originally recommended the 37 marker test by FTDNA to maintain a degree of ambiguity. But to be honest I think 67 is much better. Because FTDNA will report matches based on panels (so you will have the 3 panels for 37 anyway - giving the same result as a stand alone 37 test) and you can adjust your matching parameters in something like Y-SEARCH to give that ambiguity back if needed. The advantage of 67 markers is that someone who may appear close at 37 may be quite distant at 67 and someone who may have a slight distance at 37 may become closer at 67. The 67 markers can remove some false positives and help prevent you from follow the wrong path. So I will have to get mine upgraded to 67 at some stage. Unfortunately not everyone has been tested to 67 though.