DNA, the Silent Witness


‘Twissle Times’, March 2023

DNA, the Silent Witness to Where We are From

Yes, the answer IS within our grasp!

Y-DNA contains two types of markers, the Short Tandem Repeat (STR) and the Single Nucleotide Polymorphism (SNP). STRs are routinely used to identify people that we are related to, but the ‘terminal’ SNP, also known as haplogroup, tells us where we are from i.e., our ancestral location. It should be noted here that whilst many companies that perform autosomal DNA testing often provide a person’s haplogroup, this is invariably both just a prediction and an incomplete haplogroup i.e., it is not your personal terminal SNP, but that of one of your distant ancestors.

Y-DNA is passed from male-to-male only and unlike STRs which can back-mutate, SNPs do not i.e., each specific mutation is a one-time occurrence only, so every male contains a sequence of terminal SNPs that can be mapped back to genetic ‘Adam’.

FTDNA (Family Tree DNA) presents the information visually in what they call the Block Tree.

Figure 1 – A fictional Block Tree. The vertical column on the left denotes the number of terminal SNP mutations, which on average occur every 80 years. Matches and their locations are provided, as well as branch points.

Male EFHA Entwistle members who are genetically descended from the original Entwistles i.e., those who resided at the original Entwistle Hall, will have both the STRs of such Entwistles, and the terminal SNPs. By taking the Y-DNA terminal SNPs that align with the appropriate period i.e., 11th century, and earlier, and mapping them to the locations and names of other descendants today, a picture emerges. Furthermore, FTDNA hosts many Y-DNA haplogroup projects dedicated to this aim, and one may already exist that the Entwistles fall under.

Figure 2 – Using Terminal SNPs to determine Entwistle origins

 As the first Entwistle, as far as I’m aware, to take the FTDNA Big-Y 700 test I should have been full of excitement waiting for the results, as my DNA should potentially have provided the answer that we’re all waiting for i.e., where we came from. But, given the number of Prescott matches at Y-37, I was not overly surprised when my Big-Y 700 results revealed that I am genetically descended from the Lancashire Prescotts, not the original Entwistles i.e., there was a non-paternity event (NPE) which FTDNA predicts occurred in the early 1600’s. Therefore, we need male Entwistles who are not in the Prescott branch, to have their Y-DNA terminal SNPs tested.

Unfortunately, terminal SNP testing is only performed as part of the most extensive test available from FTDNA, the Big-Y 700, and the cost is $449, so this may be prohibitively expensive for many. But even a couple of people testing at this level should help us finally answer the question about where the Entwistles are from. If those who can afford the Big-Y 700 but are unsure whether they are part of the Prescott branch, or indeed another NPE branch that we’re not yet aware of, it is advised that you first undertake the Y-37 test, and then upgrade to Big-Y 700 which is just the cost difference between the two tests i.e., shouldn’t cost any more in total.

FTDNA provides Y-DNA testing at 3 levels: Y-37 ($119), Y-111 ($249), and Big-Y 700 ($449). Those male Entwistle members who cannot afford the BIG-Y 700 are still requested to have the Y-37 test if they can stretch to this as this will help us build the Entwistle pedigree. The price of all 3 levels is often discounted during holiday seasons, for example, Y-37 was reduced to $99 over this last Christmas and New Year period.

To be continued in our June 2023 issue – Real life Application for Genealogical Research.

[Stephen J Entwisle, member 120]