How Can DNA Results Help Our Search?
By Angelo Coniglio
There are several DNA testing firms that cater to the general public. Most of them actively promote their services, and can be found on the internet. The ‘Big Four’, with the main thrusts of their services, are: 23andMe (medical, genealogical, and personal ancestry); Family Tree DNA (genealogical, personal ancestry); AncestryDNA (genealogical, personal ancestry); and Genographic by National Geographic (population genetics research, personal ancestry). The first three charge about $100 for a basic test, while 23andMe and National Geographic charge about $200 for a more comprehensive test. For a detailed comparison, see http://bit.ly/DNATestVendorsCompared
The premise behind all of these tests is that humans, like all living things, have a ‘genome’ – a set of biological ‘plans’ that determine the details of our existence: hair color; eye color; body shape; susceptibility to asthma, or cancer, or color blindness; ability to procreate, etc., etc.; the very things that make us individuals. These traits, however, have been passed down from our ancestors, via the ‘coding’ described by substances called Deoxyribo-Nucleic Acids – DNA. We receive some of it from one parent, some from the other. Since our parents had parents, they, too received some from each parent, meaning that part of our DNA is from our grandparents - and from our great-grandparents and our great-great-grandparents, back to the first humans.
Our DNA is contained mostly in our genes, in chromosomes, of which we have 23 ‘pairs’. Most of it is of a type called ‘autosomal’, contained in 22 of the 23 chromosome pairs. The 23rd pair is the one that determines our gender. In males, the pair comprises one X and one Y chromosome, and in females it has two X chromosomes. The DNA in the Y chromosome (paternal, or Y DNA) is passed only from male to male. Another key form of DNA is mitochondrial DNA (maternal, or mtDNA), which is passed from a woman to both male and female offspring, but isn’t further passed on by male children. These characteristics mean that paternal and maternal DNA can be compared to known DNA characteristics of various ethnic and geographic groups that existed in the distant past.
I have previously said that one of the genealogical reasons for DNA testing includes the desire to know one’s broad ethnic or national origins. Many people are intrigued by such questions. Do they have Black, or Jewish, or Native American ancestry, etc.? While the test vendors use DNA analyses to indicate a subject’s ‘ancestry composition’ I believe many researchers put undue weight on such descriptions.
For example, my 23andMe ‘ancestry composition’ shows 87.7% European, with 75.1% Southern European and 59.9% Italian. It found less than one-tenth of one percent of my ancestry is Irish or British. Not surprising, since I have previously found by traditional ‘paper genealogy’ that most of my ancestors back to the sixth generation, in the mid 1700’s, were from one of only two towns in central Sicily. It shows 5.1% being Middle Eastern or African: intriguing, but no more surprising. The ‘small print’ says that these estimates are for one’s ancestry approximately ‘500 years ago, before ocean-crossing ships and airplanes came on the scene.’
Results from other venues claim to define one’s ancestry as far back as 5,000 to 50,000 years, but I feel that such ‘ancestry’ simply refers to stages or regions that the familial forebears passed through during the long history of mankind. I happen to believe that all mankind descended from the first humans in Africa, so if the DNA studies were all completely accurate and extended far enough back in time, everyone’s ‘ancestral composition’ would be the same – 100% African.
In the future, I’ll discuss what DNA testing can do to answer the questions I’m most interested in; those surrounding ‘personal ancestry’.
Coniglio is the author of the book The Lady of the Wheel, inspired by his Sicilian research. Order the paperback or the Kindle version at http://bit.ly/SicilianStory
Coniglio’s web page at http://bit.ly/AFCGen has helpful hints on genealogic research. If you have genealogy questions, or would like him to lecture to your club or group, e-mail him at genealogytips@aol.com
