Genealogy Help & Advice

GENETIC GENEALOGY (aka DNA)
WHAT IT CAN and CAN’T DO

DNA testing is the cutting edge of genealogy. We all have seen the ads for DNA tests from Ancestry.com and 23andMe.com, but do you understand what a DNA test CAN---and CAN’T do? Do you know there are three kinds of DNA tests?

Well, here’s the skinny on DNA testing. Let’s start with the CAN’Ts and CANs of DNA.

A DNA test……

…… CAN’T give you the names of your ancestors

…… WON’T disclose any deep dark secrets about you

…… CAN’T tell you an exact location where they lived

…… CAN connect you with others researching your family

…… CAN confirm your paternal line (if you are male)

…… CAN give you GENERAL locations where your deep-ancestors lived

…… CAN help confirm speculated relationships

…… CAN point you in the right research direction

What is DNA? Dictionary.com’s definitions reads:

Genetics. deoxyribonucleic acid: an extremely long macromolecule that is the main component of chromosomes and is the material that transfers genetic characteristics in all life forms, constructed of two nucleotide strands coiled around each other in a ladderlike arrangement with the sidepieces composed of alternating phosphate and deoxyribose units and the rungs composed of the purine and pyrimidine bases adenine, guanine, cytosine, and thymine: the genetic information of DNA is encoded in the sequence of the bases and is transcribed as the strands unwind and replicate.

A DNA test evaluates the patterns of the 4 bases at numerous locations, looking for STRs, Short Tandem Repeats, which are counts of repeated genetic code at given locations on each chromosome. So, all you get is a series of numbers,

If you really want to take a DNA test, you need to decide WHICH kind of test to take. That is all determined by what you want to learn, what your goals are.

The 3 types of DNA tests are

Y-DNA which can only be taken by men since only men have a Y-Chromosome. The patterns on the Y-Chromosome are not changed by the mother’s DNA, so they go virtually unchanged for thousands of years. A computer application can analyze two or more men’s results and estimate how long ago their common ancestor lived.

One way we are using Y-DNA is as follows. The Kirkpatricks of Closeburn Scotland lost all of their family records when the manor house burned to the ground in 1748. This makes it almost impossible for individuals to make a family tree connection to this line using paper documents. We have tested a descendant of Sir Roger Kirkpatrick and have his results for a baseline. We can run the application with the baseline results and another man’s results. This will tell us if the other man is a descendant of the Closeburn line.

Another instance is in my own family line. My 4^th great grandmother, Sally Finley, had 5 children. She and her 5 children inherited the lion’s share of Caniels Corley’s estate. To top that off, all five of her children took versions of the name Corley as adults. For over 100 years family members had tried to figure out who Sally Finley actually was. Was she Caniel’s widowed daughter? His daughter-in-law? His mistress? We all had our favorite theory. We got our answer after I had a Y-DNA test run. It showed that my 3^rd great grandfather was the son of a Corley, most probably Caniel.

FamilyTreeDNA.com is the only one of the “Big 3” DNA test companies that is still doing the Y-DNA tests. Their tests start at $139 for a 37 marker test, $228 for a 67 marker test and $309 for a 111 marker test.

Y-DNA Matches are presented like this:

mtDNA (Mitochondrial DNA) is passed down from a mother to her children. mtDNA can be trace directly up the maternal line, like the Y-DNA. Since in our society a woman changes her surname when she is married, mtDNA is harder to use than Y-DNA.

FamilyTreeDNA.com is the only one of the “Big 3” DNA test companies that is still doing the mtDNA tests. This test cost $169 for a full sequence test.

atDNA (Autosomal DNA) is the one you see advertised by Ancestry.com and 23anMe.com. Since we all have 46 chromosomes (22 pairs of autosomal chromosomes and 2 “sex” chromosomes) Each adult inherits half of their DNA from their father and half from their mother. Taking that back another generation they get ¼ from each grandparent. Continuing on they get 1/8 from each great grandparent – 1/16 from their great great grandparents – 1/32 from their 3^rd great grandparents and so on back to their 5^th great grandparents or 8 generations. The larger the matching segments, the closer the relationship. By determining the size of the matching segments the genetic genealogists can determine at which generation the match occurred.

Another thing an atDNA test does is to expose something called your “admixture” or heritage. Basically, it can tell you where your ancient ancestors came from. I had my atDNA tested with three companies. Below are the 3 different graphic displays of my admixture. You will see they aren’t exact matches but have similar results.

atDNA tests are offered by Ancestry.com for $99, 23andMe.com for $99 and FamilyTreeDNA.com (Family Finder Test) for $99.

Each company's admatch displays and mat displays follow: