Today's a good day to let loose those fiery locks and be proud of that natural red hair. Nov. 5 is "National Love Your Red Hair Day." Two red-headed sisters, Stephanie and Adrienne Vendetti, began this campaign to help people with red hair find confidence and build awareness for the lack of beauty and skin care products that cater to people with a fairer complexion and red hair color.The sisters have since started their own website, a monthly beauty supply box and hold events across the country that they say cater to making redheads feel beautiful and take pride in their uniqueness. In celebration, we've collected four interesting facts that redheads should take some pride in.1. Redheads only make up 2 percent of the World's populationIt's not known exactly how many red-haired people make up the world's population, but it is expected to be nearly 2 percent according to an estimation by BBC News.Red hair is more prominent of a trait for Northern Europe and there are an estimated 20.4 million people who have red hair in Britain and Ireland. An estimated 2-6 percent of the United States population carries the red hair trait. 2. Redheads with blue eyes are even more rareBoth red hair and blue eyes are expressed through recessive traits in the genes. So, taking that fact that only two percent of the world carries the recessive trait for red hair and only 17 percent have the recessive trait for blue eyes, you have a pleasant uniqueness to carry both.Most redheads have brown, hazel or green eyes.3. Those with the red-hair trait are more sensitive to thermal pain and more resilient to anesthesiaAccording to a published medical study, redheads are more sensitive to thermal pain because of a mutations to their melanocortin receptor (MC1R). As a result of this mutation, their skin is more sensitive to temperatures and they are resistant to anesthesia.These receptors help modulate pain and the study found that any subcutaneous lidocaine provided had a less significant effect on women with red hair.4. Redheads may not be around in 100 years.With the further globalization of people and the recessive traits of the genes that make red hair so vibrant, over time there may be fewer and fewer redheads around. Scientists in a National Geographic article in 2007 said that the red-headed gene could disappear by 2060. They said that the gene could just go dormant before reappearing after a few generations.Contact Devin Rodriguez at [email protected] or Follow Dev_Reports on Twitter.