Over the past twenty years, DNA testing has made it possible to trace the ancient origins of the Cotton line back to the Y Chromosomes R1b Haplotype most common in Northern Europe. The R1b paternal haplogroup first arrived in Europe 35,000 to 40,000 years ago with the highest concentrations of R1b in modern Europe being 80% in England, Ireland, Brittany in France and the northern coast of Spain.
More specifically, Cotton line DNA is R1b1a2a1a1b4f, a subclade often referred to R-L21, and has been further refined to R-ZZ7 which is associated with the Clan Byrne in the Irish Sea modality.
This subclade within R-L21 is defined by the presence of the marker L159 and is known as L159.2 because of a parallel mutation that also exists inside haplogroup (L159.1). L159.2 appears to be associated with the Kings of Leinster and Diarmait Mac Murchada and the Kingdom of Dumnonia centered in the area later known as Devon including Cornwall and parts of Somerset and Dorset as its eastern boundary changing over time.
In pre-Roman times Dumnonia had mostly a subsistence economy with no dominant elites, and many individual farms. Around AD 55, the Romans established a legionary fortress at Isca Dumnoniorum, modern Exeter, but west of Exeter the area remained largely un-Romanized. Most of Dumnonia is notable for its lack of a villa system though there were substantial numbers south of Bath and around Ilchester, and for its many settlements that have survived from the Romano-British period. Although subjugated by about AD 78, the local population could have retained strong local control, and Dumnonia may have been self-governed under Roman rule. Geoffrey of Monmouth stated that the ruler of Dumnonia, perhaps about the period c290–c305, was Caradoc (Caractacus), who was said to have been the trusted advisor of Eudaf Hen (Octavius the Old).
King Arthur is often said to have been a member of the royal house of Dumnonia, his traditional successor, Constantine, being identified with the Constantine denounced by Gildas as the "tyrant whelp of the filthy lioness of Damnonia". Geoffrey of Monmouth said that Arthur was conceived at Tintagel Castle.
Irish Kingdom of Leinster
Celtic Tribes in the south of England
R1b Haplogroup Distributions in Europe
Dedicated to the descendants of Rev. John Cotton of Boston (1584 - 1652) along with his ancestors & congregations.