Although the origin of the Jermy surname is not known with any certainty, the Jermy family has a well established history dating back to the 13th century, with the first recorded person being Sir William Jermy, who was living in Norfolk, England in 1221. His descendants established a number of branches in Norfok and Suffolk, reaching their zenith in the mid-17th century, after which the family slowly dwindled in importance, until the old land-owning family became extinct with the death of William Jermy of Bayfield in 1752.
In addition to this main family there is plenty of documentary evidence that there were other families bearing the same surname, from at least the 17th century, but who had no known link to the well established and recorded family. In all known cases these families lived in either Norfolk or Suffolk, or had their origins in these counties.
The Jermy surname itself has been recorded over the centuries with a number of variations, including Jermany, Jermey, Jermyn, Jarmy, Jarmany, Jarmay, Jarmyn, Germy and Germany. Most of these can probably be attributed to parish clerks writing down names they thought they heard when spoken by someone with an East Anglian accent. Families have had their surnames recorded using all of the above variations within the space of one generation, so it is clear that no one surname variation is strictly linked to any specific family branch. However, the Jermyn surname is a well established surname in its own right, also having its origins in Suffolk. It is possible therefore that people currently living, who have the Jermy surname, may be descended from unrecorded branches of the original Jermy family, the smaller recorded branches or from descendants of the separate Jermyn family.
The vast majority of Jermy family genealogical researchers, from all over the world, have discovered that their ancestors originated in Norfolk or Suffolk during the past several hundred years, but very few have been able to prove a connection to the old established family. The only exceptions seeming to be through marriages to female Jermys sometime in the past. Some of the branches can be traced back to the 16th century with an "original" surname of Jermyn or Germy, whilst others can only be traced back to the 18th century with surname variations such as Germany or Jarmany.
Are all these family groups somehow related? With such an unusual surname as Jermy, and one which can unfailingly be traced back to Norfolk or Suffolk, it is quite likely that all currently living Jermys originate from a small number of Jermy ancestors. There are of course large gaps in the documentary evidence that could be used to establish a connection between all the various family groups currently living around the world. The availability of Y-chromosome DNA analysis provides a way of determining the male to male lineage, which forms the basis for this project. Because of the nature of the Y-chromosome this project hopes to fulfill the following objectives:
There are two types of DNA test that are useful for genealogical testing; the Y-chromosome (Y-DNA) test and the mitochondrial (mtDNA) test. The mitochondrial DNA test can be used to establish a direct female line, but in order to trace the surname which is usually passed from father to son, it is necessary to carry out Y-chromosome testing.
Y-chromosomes are inherited from father to son and remain mostly unaltered from generation to generation. This makes the Y-chromosomes an ideal focus for genealogical studies because, barring adoption or illegitimacy, the Y-markers will follow the surname. By determining the Y-markers of males bearing the same or similar surnames it is possible to determine, with a high degree of confidence, whether or not the Jermy males have a common paternal ancestor.
While Y-chromosome markers are handed down from father to son mostly unchanged from generation to generation there is a small probability that a mutation will occur for each birth. These mutations are not a completely random process and are predictable to a certain extent. Each specific location on a chromosome has its own mutation rate, but at present the specific rates for each are unknown. An overall average is about one mutation every five generations.
Because of the random nature of these mutations probability is used to estimate the Time to the Most Recent Common Ancestor (TMRCA). If all 12 markers match for two Jermy males there is a 50% probability that the most recent common ancestor is within 14 generations or less. As the probability level increases, and the confidence that the estimate is correct, so the TMRCA becomes greater. If there has been a mutation of one of the markers so that only 11 of the 12 markers match then the TMRCA is increased again, meaning the common ancestor is a greater number of generations back in time. If two Jermy males have had all 25 Y-chromosome markers tested, and they all match there is a 50% probability that the most recent common ancestor is within 7 generations or less. If two males of the same surname have more than 3 marker mutations it is very unlikely that they are related at all.