Redheads, just saying...

 A 2004 study showed that redheads require, on average, about 20 percent more general anesthesia than people with dark hair or blond coloring. And in 2005, researchers found that redheads are more resistant to the effects of local anesthesia, such as the numbing drugs used by dentists.  Studies have also shown that Irish, and particularly Redheaded Irish, have a higher alcohol tolerance threshold.

Reheaded-ness is a recessive gene linked to the gene for pain tolerance, discomfort, being cold, irritability. I was often teased, people asking "you got a hot temper Red?  That really pizzed me off!!