Red hair is a genetic mutation.
Red hair is seen on the heads of only four percent of people. Most of these exist in the U.K., the Republic of Ireland, and Australia.
The highest percentage of natural redheads in the world is in Scotland (13%), followed closely by Ireland with 10%. In the US, about 2% of the population are natural redheads.
There is a belief that redheads are prone to industrial deafness. This actually could be true as the melanocytes are found in the middle ear.
The color Green tempers red. Look at a color chart. This is why redheads are taught as children to wear lots of green. As if red hair is a shameful state of being.
In the early 1600s, at the end of the reign of Queen Elizabeth I, the belief of Pixies (aka fairies) emerged in southwest England. They were then and have since been strongly associated with red hair for their mischievousness and otherworldly talents.
A 2002 study found that redhead are harder to sedate than any other people requiring twenty percent more anesthesia. Inadequate doses cause people to wake up during surgery and have increased recall of procedures. (I can vouch that study is accurate)
Adults have about 120,000 hairs on their head; redheads have fewer, blondes have more, brunettes have the most.
Harvard Dermatologist Madhu Pathak calls redheads "three-time losers" because their red pigment is an inadequate filter of sunlight and their skin is more susceptible to sunburn, skin cancer and wrinkling with age. Wear your sun block !!! We are not losers though.
Red headedness is, genetically speaking, a recessive trait. It may appear after several generations of darker hair.
Redheads don't turn grey. Red hair turned sandy, then white. They are also found to loose their color later in life than people carrying other hair colors.
The perception of the color red, scientifically speaking, enhances the viewers metabolism and increases heart rate and respiration.