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 1950s 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 STRs, 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 1300s, 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 SNPs), My Heritage, and Ancestry.
So let me illustrate all this theory with some Blackett data. First, my STRs, which I typed in the crime laboratory, can be seen in an article I co-published with a stamp collector.
My family data was also used on a university genetics website for teaching, both STR and the older RFLP technology.
Next, I had my Y chromosome STRs tested by Family Tree DNA at 37 loci in 2008. My Y haplogroup is R-M512, a fairly common Eurasian type and subgroup of R1a.
DYS393 13 DYS390 25 DYS19 15 DYS391 10 DYS385 11-14 DYS426 12 DYS388 12 DYS439 10 DYS389I 13 DYS389II 29
DYS392 11 DYS458 15 DYS459 9-10 DYS455 11 DYS454 11 DYS447 23 DYS437 14 DYS448 20 DYS449 35 DYS464 15-15-15-16
DYS460 12 Y-GATA-H4 11 YCAII 19-23 DYS456 16 DYS607 16 DYS576 18 DYS570 18 CDY 33-41 DYS442 12 DYS438 11
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 (A 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.
Finally, I very recently had My Heritage type my DNA for ethnicity, a Christmas sale for only $49! The results are shown 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, Vikings, 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 hope this summary is helpful. I find it fascinating. I would be interested to compare to other Blacketts.
31 Jan 2018
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.