DNA Testing


DNA testing for family history research

The Human Story

Humans split from chimpanzees about 5 – 7 million years ago.  In 1974 the remains of ‘Lucy’ were found in Ethiopia.  She lived about 3.2 million years ago and belonged to the Australopithecus era.  

Between about 770 thousand and 550 thousand years ago Neanderthals and modern humans split genetically; 320,000 years ago we see our most recent ancestor.  In case you are interested, dinosaurs lived way before this time, 65 million years ago.  Between about 70,000 and 50,000 years ago we start seeing the divergence in the human tree of movement from Africa to West Africans, East Africans, West Eurasians, East Asians and Native Americans

All modern humans share common DNA from Africa and 99.9% of DNA in humans is identical to each other.  This makes sense when you consider that humans are basically the same.  Mutations are only found in 0.1% of DNA and it is those mutations or differences in the 0.1% that tell us how closely two people are related to one another. 

double helix
Double Helix

So, what is DNA?

DNA stands for deoxyribonucleic acid.  It was first isolated in 1869 as a nuclei.  In 1953, Brits James Watson and Francis Crick suggested the first correct double helix model. In the nucleus of each cell, the DNA is in thread-like structures called chromosomes.


We each have 23 pairs of chromosomes called autosomes.  Of the 23 pairs, 1 pair are the sex chromosomes XX = female and XY = male

DNA is measured in centimorgans (cMs); each person has a maximum of 6800 centimorgans.

So why is DNA of interest to genealogists?

There are many reasons why genealogists are increasingly using DNA in their research. For existing genealogy research, DNA can be extremely useful in:

  • validating existing research
  • bridging gaps in paper records
  • resolving brick walls
  • finding mistaken connections in genealogy trees
  • confirming and/or identifying non-paternal events (NPE’s), e.g. illegitimacy and adoption

Additionally, from an EFHA perspective, it could be used to:

  • identify the ‘Most Recent Common Ancestor’ for EFHA members
  • identify the major branches of the EFHA genetic tree
  • improve understanding of the evolution and variants of a surname
  • identify the origin of that surname and the DNA link to the ancestral country

Which company should I use?

There are several companies offering ancestry DNA service, but there are important differences between them. We will provide a more detailed breakdown in a future article, but given Christmas is a time of giving, and increasingly the giving of DNA test kits, we felt that we should provide some guidance here. Differences include:

  • the ability to create genealogy trees on the company platform, and to link DNA test results with these
  • the size of the company database
  • the download of raw data
  • the type of DNA tested
  • the means to contact DNA cousins

Given that readers of this article will most likely want to further their genealogical research, it could be argued that AncestryDNA is the best starting point. However, the major caveat is that because of the type of DNA tested, it only provides data 7 – 10 generations back from the person having their DNA tested.

If one is interested in one’s ancient family lines then it could be argued that ‘23 & Me’ provides a good starting point, although personal experience is that the 23 & Me database seems to have a much greater bias toward USA cousins, and it is said that 23 & Me testers tend to have a lower genealogical knowledge, or interest, than AncestryDNA testers, so may not provide much assistance even if cousin connections are made.

From a talk by Steve Entwisle, member 120 & Janet Durham, member 388

Any errors and misunderstandings are the responsibility of the ‘Twissle Times’ Editor.