It might seem a little uncanny, but a recent genetic research shows that there are strong similirities between the Y chromosome haplotypes from the males of northern-western Spain and of Portugal with the Irish men who often appear with Gaelic surnames, but not just that group.
The frequency of Y-DNA haplogroup R 1b which is the most common haplogroup in the continent of Europe, is in fact the highest in the populations of the Atlantic Europe, and also due to the mass European emigrations, it is also very common in North America, South America and Australia. Another example is Irland and the Basque country, this haplogroup’s frequency exceeds 90% and approaches 100% in Western Irland.
The incidence of R1b is almost 70% or even more in the Celtic regions of Cumbria and Cornwall in England, also in the Celtic North region of Portugal (Douro, Minho, Trás-os-Montes e Beira Alta), Northern Spain (Celtic Galicia, Asturias, León, Cantabria and Basque Country), Western France (Béarn, Gascony, Guyenne, Saintonge, Augoumois, Aunis, Poiton, Touraine, Anjou and the Celtic Brittany) and of course the six Celtic countries which remained Celtic speaking throughout the Middle Ages ( Brittany, Wales, Cornwall, Isle of Man, Ireland and Scotland).
The R1b’s incidence declines gradually with distance of course, but it is still very common across the central areas of Europe. For example, the R1b is the most frequent haplogroup in Germany and in the low countries, and is common in Southern Scandinavia as well and in Norther Italy.
The majority of Irish people and all natives from the British Isles primarily descend from an “Iberian refugium” population dating back to the last ice age.
These connections got stronger when the Celts started their migrations during the late Bronze Ages (1200 BC) and spread all over Europe, thousands of Celtic tribes that settled in so many European regions forming the first nations of each individual country we have today. For example the Lusitanians (which probably had another name since they are of Celtic origins and the name was given to them by the Romans in the late Iron Ages) a Celtic tribe that settled in Central Portugal, its with them that the History of Portugal begins in terms of the very first portuguese nation to be formed in portuguese territories. This tribe of Celts had strong connections with the other Celtic tribes of North-Western Spain (Galicia) all the way to today’s Austria via trade routes that linked the Celtic World. When the first Celts invaded Irland and settled there, one of the major Celtic tribes that went there were in fact the Lusitanians, almost a 1000 years before the Celts gradually infiltrated Britain.