Two sneezes mean twice the velocity

Have you ever noticed that, in general, some people only sneeze once at a time and some always sneeze twice? Have you ever wondered why this happens? Well, there may or may not be a definite answer. First, some folklore from the Persians and Japanese:

A widespread belief in Persian folk tradition considers a single sneeze to be a sign that you have to stop whatever you are doing. This is called sabr Amad (patience is in order). A double sneeze is a sign that you should speed up whatever you are doing. The Japanese believe one sneeze means someone is speaking highly of you and two indicate someone speaking ill of you.

People often sneeze twice when they are doing absolutely nothing. Additionally, people sneeze at odd hours of the day when other people are most likely asleep and not speaking of anyone at all. So, we must turn to science. An early experiment was performed in the Monday, Sep. 02, 1940 issue of TIME:

Dr. Milton Hyland Erickson, director of psychiatric research at Eloise Hospital in Michigan, observed a young woman who, when she sneezed, nearly always sneezed twice in rapid succession. After one sneeze she waited for the second and if it did not come felt “a distressing sense of incompleteness.” Checking the sneeze behavior of the woman’s mother, he ran into another double-sneeze pattern. When a granddaughter was born, Dr. Erickson kept careful record of her sneezing, found three generations of double sneezers. In his report in the current Journal of Genetic Psychology, he concluded: “Variations in the [sneeze] pattern may be inherited.”

A similar condition, the photic sneeze reflex (sneezing when introduced to light), which affects 18-35% of the population, is inherited as well.