Among the various hair colors of the world, black and brown are the most prevalent by a wide margin (particularly in Africa and Eastern Asia), blonde is less common but still widespread, and red is the rarest of all, possessed by roughly two percent of the world's population. Without question, the countries of Ireland and Scotland have the highest percentage of people with naturally red hair. However, precisely what those percentages are and which country's percentage is ultimately the highest is a bit less clear.
People with red hair are treated differently in many cultures. In Polynesia, red hair is considered a sign that one's ancestors were of noble status. At different times in history, Europeans have considered red hair a sign of immorality, Judaism (which was persecuted at times), or even lycanthropy or vampirism. Redheads are occasionally referred to as "gingers", but this term is often considered disrespectful when used by non-redheads.
What causes red hair? Genetically, red hair is the result of two recessive genes located on chromosome-16. When both of these recessive genes are expressed, they modify the MC1R protein, which helps encode the body's skin and hair pigmentation. This modification results in not only red hair, but also additional characteristics including very light/fair skin, possible freckles, heightened sensitivity to temperature and UV/sunlight, and increased pain tolerance.
While natural hair color is always controlled by genetics, scientists have suggested that environmental factors can play a role in determining which genes (and therefore colors) become more dominant in a given region. In fact, the United Kingdom's high redhead population is believed to be caused, at least in part, by the weather.
According to the theory, redheads' heightened sensitivity to sunlight enables their bodies to generate vitamin D more efficiently—which makes redheads slightly better-suited to the UK's frequently cloudy weather. Over generations, those slightly healthier redheads produced slightly more healthy children, who had a slightly higher survival rate, eventually leading to the area's world-leading frequency of redheads.
By most estimates, the European Country Ireland has a higher percentage of redheads than any other country in the world, with the latest estimates suggesting that approximately 10% of the country's population have red hair. For comparison, in most places across the globe, redheads make up no more than two percent of the population.
Another Western European country, Scotland may be the only other country on Earth with a percentage of redheads comparable to that of Ireland. Some estimates suggest that the percentage of redheads in Scotland is roughly 6%, though other estimates place it as high as 13%—higher even than Ireland. Much like their Irish counterparts, the residents of Scotland are known for having a greatly increased likelihood of red hair, which helps explain why people in other parts of the world so often assume that people with red hair must be of Irish or Scottish heritage.
A member of the United Kingdom along with Scotland, Wales, and Northern Ireland, England has long been recognized for its higher-than-average percentage of redheads, which computes to roughly 4%. With the exception of Ireland and Scotland, red hair is more common in England than most anywhere else in the world.
The percentage of red hair in the United States is elevated, with estimates ranging from approximately two to six percent (2%-6%). Although this is notably below the percentages of red hair in Scotland and Ireland (and possibly England, depending upon the source of the estimate), because the United States is also the third-largest country in the world in terms of total population—behind China and India, two overwhelmingly dark-haired contries—the US actually houses a greater total number of redheads than any other country on Earth.
The US was reportedly home to up to 18 million natural redheads as of 2018, more than the combined total (all hair colors) populations of Ireland (seven million) and Scotland (under six million) combined and easily the largest population of redheads in the world. It is notable, however, that the majority of US redheads are believed to have Northern European ancestry.
Although the Jewish people are spread across many countries, it is estimated that as many as 10% of Jewish men have red hair or beards. An example is the Ashkenazi Jews, who originally settled in France and Germany during the Middle Ages. Approximately 3.6% of Ashkenazi women and 10% of Ashkenazi men have red hair. According to a study that took place in 1903, approximately 5% of Jews in Poland had red hair, though more current data has yet to become available. Throughout much of Europe, red hair is considered a Jewish trait.
The Netherlands hosts one of the largest redhead-themed celebrations in the world: the annual Roodharigendag("Redhead Days") festival, which attracts thousands of attendees from all around the globe. France, which has the highest Jewish population of any country outside of Israel and the United States, may be as much as 5% redheaded.
In Africa, the majority of people with red hair live among either the Riffian people of Morocco or the Kabyles of Algeria. Princess Lalla Salma, the wife of King Mohammed VI of Morocco, has naturally red hair.
In Asia, the Middle-Eastern countries of Jordan, Palestine, Lebanon and Syria have a higher percentage of redheads than the rest of the continent, likely due to the emigration of red-haired individuals from Europe. However, several other countries have either geographical regions or specific ethnic groups known for a higher frequency of red hair.
The Uyghurs, a Turkic ethnic group who live primarily in China, but with a presence in Kazakhstan, Pakistan, Turkey, Kyrgyzstan, and Uzbekistan, have an above-average concentration of red-haired people. The Udmurt people, who reside in the Volga Region of Russia, enjoy a similar reputation. Finally, a tiny number of Polynesians people also have reddish-brown hair, and as a result are often regarded as having regal ancestry.
Ireland has more redheads than any other country, with around 10% of the population having red hair.