Post by taf
The main problem is that most burials from the period cannot be identified by name, and those that can are not allowed to be studied. There are a few cases of a medieval burial being identified by DNA analysis, like in the Richard III case or, depending on when you draw the cutoff, Copernicus.
It is hard enough to come up with a medieval person with a known burial around whom there is a standing genealogical question. Something like the maternity of William Longespee, if that wasn't learned a couple of decades ago through traditional documentation. Then you would need a to be allowed to do the exhumation, unlikely if
the purpose was solely genealogical curiosity. And for most genealogical questions, you would need a second test subject as well. It doesn't surprise me there have been no instances.
There are 3 kinds of DNA tests for genealogy: autosomal, Y and MT.
Autosomal is usually considered as limited to 6 generations backward,
i.e. cousins you may find should be 12 generations distant, roughly
6 up and 6 down. For someone born 1900, 6 generations at 50 years each
go back to 1600 which is a limit as to where you can find a link
between 2 living persons (if their DNA was sampled in year 2000).
Typically, it would be someone born around 1940 and generations of
30 years. So, from a medieval burial (or someone buried before 1600
for this discussion), you may get a tiny link between that person
and a living person but likely of the noise level, i.e. too small
to be meaningfull.
However, the link between 2 persons of the same time could be
estimated. Is that the son/father of the other for example. But
you will need 2 burials for that purpose. This happens in some
medieval or old burials where there is some comparison of 2
persons found at the same place, but not enough to identify them.
Y and MT are more interesting. In both case, you must have a
continuous lineage to the tested person. That lineage doesn't need
to be from that person as it can be from a sibling, cousin, etc.
With Y, if you can perform a Big Y test (DNA must be in very good
state), you can get an estimate along the generations line. For
example, if John buried in 1400 has a brother Sam who has 2
living male descendants from 2 sons and each performs a Big Y,
then you can estimate the number of generations between John
and Sam (Big Y 700 is presumed to find 1 SNP per 2 generations).
Without a Big Y, you have nonetheless some matching between
John (the buried man) and the descendants of Sam (the reference
DNA). Less accurate that the Big Y 700, it will say if they are
probably (or not) of the same family. There are already matches
known for descendants of a common ancestor living before 1600.
The MT DNA is similar except you will need a female lineage from
the mother of John. If Sam is a full sibling or Mary is the sister
of John, then a descendant in matrilinear lineage of either Sam
or Mary will do the job.
In all these cases, you must know who was buried and the DNA
tests will only confirm it is **likely** that person.
Denis Beauregard - généalogiste émérite (FQSG)
Les Français d'Amérique du Nord - http://www.francogene.com/gfan/gfan/998/
French in North America before 1722 - http://www.francogene.com/gfna/gfna/998/
Sur cédérom/DVD/USB à 1790 - On CD-ROM/DVD/USB to 1790