Welcome, visitor! The global Drennan Surname DNA Project aims to supplement genealogical research on Drennan families with genetic evidence in hopes of further developing the Drennan family tree. Most families using this surname are thought to be of Irish Celtic origins, the name coming from O'Draghnain or O'Draighneain, "dweller at a blackthorn." The name was recorded as early as the year 1163, with the death of Gillachiarain O'Draighnen of Fore Monastery in County Westmeath. The Irish poet Dr. William Drennan is credited with giving Ireland her nickname, "The Emerald Isle." The surname likely arose independently in various locations, both in Ireland and elsewhere, and it is now found in many parts of the world. People who think they might bear any variation of the surname or descend from an ancestor who bore any variation of the surname from any part of the world are welcome and encouraged to participate in the Drennan Surname DNA Project. Using DNA testing, the Drennan Surname DNA Project can help tell us which family lines are related, confirming or refuting lineages with established paper trails and pointing the way for further research for other lineages. It can also reveal particular DNA signature variations for particular family lines, enabling us to place previously unlinked families into their respective branches of the Drennan family tree. Males who descend from a Drennan along their all-male ancestral line may participate in the project through Y-DNA testing. Anyone who descends from a female Drennan along his or her all-female ancestral line may participate in the project through Mitochondrial (mt) DNA testing. Anyone who descends from a Drennan along any of his or her ancestral lines may participate in the project through Family Finder (autosomal) DNA testing.