DNA tests carried out in early 2006 between two Dungate males (with no known connection prior to the test) and two Dengate males (known to be distantly related with a shared common ancestor within 5 generations) came back with a definite, conclusive DNA match. This placed a common ancestor to around c.1600, when the name would have split between Dengate and Dungate.
Further tests carried out in March 2008 on Dengate males from Ticehurst and the Wittersham Tree also proved to be connected to the others who had already been tested. This lends substantial weight to the theory of there being a single Dengate / Dungate family. Any deviations from this would be caused by illegitimacy. Further Dengates and Dungates are required to take the test and the more people take part in the test, the more focused the conclusions that can be drawn in establishing the long-term history of the family.
Unfortunately, these tests were conducted with DNA Heritage, which has since closed for business, so some of the work was lost.
However, in 2019 I established a new D*ngate DNA group with FamilyTreeDNA. The group and its results can be found here. So far, the project has six D*ngate participants, all of whom have have a proven DNA connection, despite there currently being no paper trail to link some of them. The current results point to a split between the Dengate and Dungate name in the early-mid 1600s.
More participant are needed! If you are a Dengate or Dungate male, please consider taking the test (a simple swab from the cheek area inside the mouth). Alternatively, if you would like to contribute towards the cost of a test, there is a donation button on the project page at Family Tree DNA. Thank you!