Blondes may stereotypically have more fun, but some studies show those born with red locks might feel more pain. So we all need to treat our ginger-headed friends more gingerly since research shows they're more sensitive to hot and cold, and strangely, redheads also require more anesthesia to become numb.
For those with brown, black, and blond hair, the Melanocortin-1 receptor (MC1R) gene produces melanin, which gives our hair and skin color. In redheads, this gene is mutated and produces pheomelanin instead, causing pale skin, freckles, and strawberry tresses. MC1R mutations also affect carrot tops' perception of pain and the effectiveness of drugs that are used to block the sensation of pain.
Not only is this research interesting (and may explain why your friend screamed her red head off when she got her ears pierced), but it may also help scientists design drugs that are more person-specific based on an individual's genetic profile.
If you're a redhead, please share your thoughts on this hairy subject.