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About us

The Grannum DNA Project welcomes all participants. Join today.

This is a new project and we are excited about the opportunity to use DNA analysis to complement documentary and archival research to the better understand the origins and history of the name and to bring families and relatives together.

Grannum is a registered on the Guild of One-Name Studies (member 1404). The administrator has been researching the name for over 20 years and has found that Grannum is first found on the Caribbean island Barbados in the 1740s and until the late 1700s was interchangeable with Granham. The name originates from a William Crannum who married in Barbados in 1735 and is believed, but not proven, to be the same William Crannum who was transported from Gloucestershire, UK to 'America' (country unknown) in 1723. See for more information on Grannum research.

In common with other Caribbean families Grannums have migrated to other Caribbean countries especially Jamaica (c1900) and  Trinidad, and to Panama, Canada, Guyana (c1820s), USA, Scotland (1870) and England (1950s); some families live in Germany (c1980s) and South Africa (c1930s).

Traditionally, in the UK and other Anglophone countries surnames are passed on from father to son. The Y-Chromosome is passed from father to son and so usually there is a close match between DNA and surnames.

However, the social history of Barbados means that this pattern does not apply. Barbados was a slave economy and enslaved and free Africans adopted local surnames and many parents were not married meaning that children were registered with their mother's surname. Also, documentary evidence is incompete especially for African-Caribbean families before the 1840s.

See for more information on the challenges of Caribbean genealogical research.

It is hoped that by analysing the DNA (Y-Chromosome) of men with known Grannum paternal line (ie father's father's father etc) and comparing this with documentary evidence it will possible to bring relatives together.

The Y-chromosome is only passed from fathers to sons, women do not inherit this chromosome. If you wish to test your paternal line women will need to obtain swabs from their father, grandfather, brothers, cousins and uncles etc. It is recommended that your test looks for a minimum of 37 markers (the more markers the better). If you order fewer markers you can upgrade later but this costs slightly more.

Unusually for a surname project it would be useful to obtain Mitochondrial DNA which is passed from mother to sons and daughters; typically this analysis is used to trace the maternal line. Women who have a proven Grannum grandmother or greatgrandmother or earlier are welcome to participate.

A final test is the FamilyFinder which looks at the 23 pairs sex chromosomes half of the chromosomes come from your mother and the other half from your father. A proportion of ancestral chromosomes will be inherited by children, grandchildren etc and will be shared by siblings, aunts, uncles and siblings. The proportion diminishes over time but this test can be a useful tool to match distant cousins who have common ancestry over about 5 generations. This test also aims to show overall ethnic mixtures for all of your ancestors. explores what the results of three tests can show. I hope to update it showing how the tests have helped link and extend a couple of Grannum family trees.

Go to to join this project if you have already had DNA tests carried out by FTDNA or to order a test.

If you have not had tests carried out by FamilyTreeDNA you can upload your results and compare them with others at: