Although genetic genealogy has three main approaches, namely Y-DNA, mitochondrial DNA, and autosomal DNA analysis, the optimum method for a surname project is Y-DNA analysis. The Y chromosome is passed essentially unaltered from father to son, unlike other chromosomes which comprise a combination of paternal and maternal DNA. (Aside: although a male only receives an X chromosome from his mother, this X chromosome contains a combination of DNA from the X chromosomes of both of his maternal grandparents). Therefore all male Creeds descending from the same Creed patriarch should have near-identical Y-DNA results. Rare and random variations (sometimes termed mutations) do occur, which have no biological significance, and which can assist in determining the likely degree of the relationship between two matching individuals.

The Creed surname has historically been adopted independently by several unrelated families. That this project contains Creeds who do not match one another genetically should therefore come as no surprise. When two Creeds match one another genetically we know that they share a common ancestor along a pure paternal line, who was almost certainly also surnamed Creed. Sometimes there will be a trail of documentary evidence tracing back to this common ancestor, but often the common ancestor will have lived too long ago for a complete paper trail to exist. When a complete paper trail does not exist, comparison of Creed pedigrees of the matching individuals can provide information that, without genetic genealogy, could not otherwise be obtained. To illustrate this point: if, for example, a member of a Creed family that can be traced back no earlier than to the arrival of a Creed patriarch in America matches a Creed from, for example, Britain or Ireland, whose Creed ancestors can be traced sufficiently far back in time to a particular location in Britain or Ireland, the likelihood is that this particular location is also the previously unknown (or, more precisely, long forgotten) location of origin of the Creed family that settled in America.

It is likely that many Creed families have British origins, where it is believed that some Creeds take their surname from the location Creed in Cornwall, which in turn was named after the 7^th century St. Crida. The surname is likely to have been adopted independently in other parts of Britain. The Creed surname also appears as native to Ireland – probably as a variant of the Irish surname Creedon, although a family of Creeds from England is known to have settled in Co. Limerick, Ireland, during the plantations of the 1600s. The Irish surname Creedon is most commonly found near Macroom in Co. Cork, where there are also several families of Creed (who may well share common ancestry with their Creedon neighbours). There are references (from between 1569 and 1621) to Creedons (and McCreedons) in counties Tipperary, Cork, and Kerry, who were all harpers. Creedons may have originated in the province of Ulster, before later settling in Munster. Although today the surname Creed is made famous by the Parisian perfume company “Creed”, the founder of that company was not French but English – James Henry Creed (1710-1798), who originally founded the “House of Creed” in London in 1760. The Creed surname has been found in North America since the 1600s, most notably in Virginia and Maryland.

The Creed surname DNA project currently contains samples from several groups of Creeds with diverse origins. Pedigrees of some of the Creed families that have participated in this project can be viewed in the “Goals” section of this project.