In 2010, scientists in Dublin successfully sequenced the first entire genome of an Irish person.
This research revealed some startling differences between the 'Irish' and that of already sequenced 'English' genomes.
With the explosion in the rate of DNA sequencing, it is only a matter of time before countless genomes from across the British Isles are available, allowing direct comparisons to be made between the English, Irish, Scottish and Welsh.
In this programme, Tracey Logan explains how analysis of DNA can be used to trace back ancestral lineages.
She considers what the results of such studies might tell us about ancient Britons and how this is reflected in the multi-cultural British Isles of the 21st century.
She asks should we be prepared to draw further lines of difference between the four nations or will we be forced to accept a shared ancient heritage?
She travels to Edinburgh where she finds a Scottish Chieftain who is fearful of the impact that hard genomic facts might have on his much-loved clan heritage.
She meets geneticists who are looking for traces of Viking ancestry amongst modern day residents of the Wirral peninsula.
She joins volunteers in Canterbury who have elected to share their DNA with the People of the British Isles Project and she decides to have her own maternal and paternal ancestral lineages revealed though DNA analysis.
Producer: Helen Toland
Tracey Logan looks at how new advances in genetics may mean a rewrite of British history.