In the past we have passed on details of a small number of Blackett descendants who have expressed a wish to compare DNA testing results with other descendants who have contacted us on the subject. We do not, however, have any experience of DNA testing and have been able to add little to the process. In future, therefore, we recommend that anyone interested in comparing DNA test results initially contact one of the major proprietary sites such as Rootsweb or ancestry.com.
You may, however, find the interesting article by Robert Blackett of Arizona which appears below to be helpful in understanding DNA. If you do decide to go ahead with DNA testing and find another Blackett descendant and wish to establish the precise relationship between the two of you, please let us have details of both parties and we will do our best to find out where you both fit in to the tree.
(NB. We can, of course, accept no responsibility for the accuracy, or any other aspects, of tests carried out following an approach to RootsWeb or any other third-party site.)
BLACKETT DNA TESTING – BY ROBERT BLACKETT, RETIRED CRIME LABORATORY DNA ANALYST FROM ARIZONA, U.S.A.
Basic Genetics: James Watson and Francis Crick established in the 1950’s that DNA is the basic genetic material. Humans have 23 pairs of chromosomes, one from each parent. 22 are ‘autosomes’. The 23rd pair are the sex chromosomes, X and Y. Males are genetically XY, inheriting the X from their mother and the Y from their father. Females are XX, inheriting an X from each parent. An individual shares half their DNA with parents, children, or siblings, one-quarter of their DNA with grandparents or grandchildren, one-eighth of their DNA with great- grandparents or great-grandchildren, first cousins, etc.
Genealogical DNA Tests: There are different types of DNA tests. They can be autosomal, looking at polymorphic regions on chromosomes 1-22. These were our main tools in the crime laboratory, trying to identify people from their body fluids. They were called STR’s, for short tandem repeats.
More useful genealogically are two types of DNA that don’t re-mix every generation. The first is Y-chromosome DNA to follow paternal lines – men inherit their Y-chromosome intact (barring mutation) from their father and pass it on to their sons. Thus if a Blackett male is descended directly from the earliest Richard Blakheved of Woodcroft in the 1300’s, their Y-chromosome should be the same.
The second type of DNA that doesn’t mix is mitochondrial DNA. All individuals, both male and female, inherit their mitochondrial DNA strictly from their mother. Mitochondria in the sperm cell don’t survive fertilization. Thus maternal lines can be followed, again essentially unchanged except for mutation, all the way back theoretically to mitochondrial ‘Eve’.
Mitochondrial and Y-DNA are wonderful to show relatedness to both paternal and maternal lines, but are less useful to show ‘ethnicity’. They do both yield something called a ‘haplogroup’, and statistics can relate that to regions of the world/human migration.
The modern DNA tests that that have become cheap and popular and best show ethnicity are done to autosomal DNA, looking at regions of the autosomes called SNPs (single nucleotide probes). It’s all done by robots, a sample of DNA (usually from saliva) is digested and attached to a genotyping chip that can be read for hundreds of thousands of polymorphs. The biggest companies are Family Tree DNA (particularly for Y and mitochondrial DNA), then 23andme (which also can do health-related SNP’s), My Heritage, and Ancestry.
So let me illustrate all this theory with some Blackett data. First, my STR’s, which I typed in the crime laboratory, can be seen in an article I co-published with a stamp collector: http://www.lindberghkidnappinghoax.com/philately.pdf
My family data was also used on a university genetics website for teaching, both STR and the older RFLP technology.
I had my Y chromosome STR’s tested by Family Tree DNA at 37 loci in 2008. The first 10 of these Y loci are as follows: DYS393 13, DYS390 25, DYS19/394 15, DYS391 10, DYS385a 11, DYS385b 14, DYS426 12, DYS388 12, DYS439 10, DYS389-1 13. My Y haplogroup is R-M512, a common Eurasian type.
But alas, your Blackett website administrator spoilsports pointed out that my paternal line was broken by a Blackett woman, Elizabeth Blackett, having a child (Cuthbert Blackett) from a Cuthbert Johnson in 1703 (History of the Blacketts p. 91), and that child was raised as a Blackett. Thus my Y-chromosome is likely ‘Johnson’. At that point I lost interest. I also in 2008 compared my Y-profile to that of Tony Blackett, from Sheffield. Tony presumably came by his Y-profile more honestly. We were very different.
Family Tree also typed my mitochondrial DNA, and my haplotype (HVR1 and HVR2 regions) is ‘K’. That is again a fairly common Eurasian type. My mother was of German descent, maiden name Schaefer.
In 2017 I had My Heritage type my DNA for ethnicity, a Christmas sale for only $49! The results can be found here.
Note the strong Scandinavian influence. European DNA is particularly mixed, and British DNA is even more mixed (influence from original Britons, then Romans, Anglo-Saxons from Germany, Danes, then Normans, who were originally evidently from Scandinavia). Likely the North of England has more Scandinavian influence, as well as Scot. My mother’s influence could be seen in the N and E European portions.
I uploaded that raw SNP data to GEDmatch about a year later - it’s free. That allows anyone to directly compare their DNA with me, no matter which private company they used (it also allows detectives to catch you or relatives if you are serial killers). A ‘Centimorgan’ number is generated for shared segments; e.g. my first cousin and I shared 962 centimorgans. In 2020 another distant Blackett relative in the Durham area compared her DNA (done by Ancestry) - there was no overlap, confirming our family tree split at least 300 years ago. If you want to directly compare to me on GEDmatch and have uploaded your data, my kit number is H922729.
I hope this summary is helpful. I find it fascinating. I would be interested to compare to other Blackett
Robert Blackett Nov 2020
If you are interested in comparing Blackett DNA results with Robert or have a technical DNA question for him please contact him at firstname.lastname@example.org.