"The red-hair gene is most common in Irish blood. The blood in Irish veins is Celtic, right? Well, not exactly. Although the history many Irish people were taught at school is the history of the Irish as a Celtic race, the truth is much more complicated, and much more interesting than that .. Research done into the DNA of Irish males has shown that the old Anthropological attempts to define 'Irish' have been misguided. As late as the 1950s researchers were busy collecting data among Irish people such as hair colour and height, in order to categorise them as a 'race' and define them as different to the British. In fact British and Irish people are closely related in their ancestry. Research into Irish DNA and ancestry has revealed close links with Scotland stretching back to before the Ulster Planation of the early 1600s. But the closest relatives to the Irish in DNA terms are actually from somewhere else entirely!