Curly hair is not a distinctively Irish trait, but it’s not uncommon among Irish people either. Among Europeans and their descendants, roughly 45% have straight hair, 40% have wavy hair, and about 15% have curly hair. Irish people fall within this general European distribution. So while you’ll certainly find curly and wavy hair in Ireland, it’s no more “Irish” than it is British, French, or Scandinavian.
What Genetics Says About Hair Texture in Europeans
Hair texture in Europeans is influenced by multiple genes, but one of the best-studied is TCHH, which produces a protein called trichohyalin that helps shape the hair follicle. A specific variant in this gene (rs11803731) has a strong association with straight hair. The more copies of this variant someone carries, the more likely their hair is straight. This variant reaches its highest frequency in Northern Europeans, which includes the Irish, Scandinavians, and British populations. It accounts for about 6% of the total variation in European hair shape, meaning many other genes contribute to whether your hair ends up straight, wavy, or curly.
The variant linked to straight hair has a minor allele frequency of about 18% across European populations. That means the majority of Europeans carry at least one copy of the “straight” version, but plenty of people don’t, leaving room for the waves and curls you see across the continent. There’s no known gene variant that’s unique to Ireland and specifically produces curly hair.
Red Hair and Curly Hair Are Not Linked
Because red hair is so strongly associated with Ireland (and for good reason, since Ireland has one of the highest rates of red hair in the world), some people assume curly hair goes along with it. Genetically, these are separate traits. Red hair is overwhelmingly controlled by variants in the MC1R gene, which accounts for about 73% of red hair heritability. MC1R affects pigment, not hair shape. The genes controlling hair color and hair texture operate through different biological pathways, even though they both involve cells in the hair follicle. You can absolutely be Irish with red, curly hair, but one doesn’t cause the other.
The “Black Irish” and Curly Hair
The idea that curly hair is Irish often traces back to the popular concept of the “Black Irish,” a term used mainly outside Ireland to describe Irish people with dark hair and sometimes darker complexions. The most common origin story claims these individuals descend from Spanish sailors shipwrecked during the Spanish Armada of 1588, who supposedly swam ashore, settled in Ireland, and introduced dark, curly hair into the gene pool.
This is almost certainly a myth. Of the roughly 5,000 Spanish sailors recorded as shipwrecked off the Irish and Scottish coasts, the few who survived were either killed by locals, handed over to English troops for execution, or quickly returned to Spain. Two genetic studies conducted in the 2010s found little to no Spanish DNA in Irish populations. Dan Bradley, a population geneticist at Trinity College Dublin, has rejected the Spanish origin theory outright.
Dark hair in Ireland doesn’t need a dramatic origin story. It’s simply common. Dark brown or black hair paired with pale skin and light eyes is one of the most frequent combinations in Ireland and has been for centuries. The Irish DNA Atlas, a large-scale genomic study, found that about 80% of “Gaelic” Irish ancestry traces to French, Belgian, Danish, and Norwegian population clusters, with the largest single contributor being a cluster from northwestern France (a region with genetic ties to other Celtic populations). A notable Scandinavian component dates to the Viking period. None of this points to a particularly “curly-haired” origin.
What Ancient Celts Actually Looked Like
Historical accounts of the ancient Celts, the cultural ancestors of the Irish, describe people who generally wore their hair long. Both men and women styled their hair in braids and curls. Roman and Greek observers typically described Celts as fair or blond, though historians note this may partly reflect the Celtic practice of using chalk or lime-water to lighten and stiffen hair. Those substances change hair texture, allowing warriors to shape their hair into spikes or tufts for intimidation.
Irish literary sources also describe elaborate hairstyles. The medieval prose epic Táin Bó Cúailnge depicts a woman wearing three braids wrapped around her head with a fourth hanging to her ankles. These descriptions tell us the Celts valued textured, styled hair, but they don’t tell us much about natural curl patterns at the population level.
Why Hair Texture Varies So Much Within Ireland
Ireland’s genetic makeup is more complex than many people assume. The Irish DNA Atlas identified seven distinct genetic clusters within the island, geographically stratified from Ulster in the north through Connacht and Leinster in the center to Munster in the south. Each cluster carries slightly different proportions of ancestral influences, including French, Belgian, Scandinavian, and smaller contributions from other European populations. The “Gaelic” Irish clusters show the lowest proportion of Germanic ancestry among all Irish and British groups, but they carry a surprising amount of Norwegian-like ancestry linked to Viking activity.
This patchwork of ancestry means hair texture varies widely from family to family and region to region. You’ll find straight, wavy, and curly hair throughout Ireland in roughly the same proportions as the rest of Northern Europe. Curly hair in an Irish person is perfectly normal and has clear genetic explanations, but it’s not a defining Irish characteristic any more than blue eyes are exclusively Scandinavian. It’s one of many traits distributed broadly across European populations, shaped by overlapping waves of migration and a handful of genes that don’t respect national borders.