Was reading the latest /. poll on sneezing when entering into sunlight and someone posted an actual reference to what it is. I do this all time, so it was interesting to read what it's all about. Turns out it is passed genetically, so you either have it or you don't and I'm curious who had in my family.

Photic sneeze reflex (also called ADCHOO, Autosomal Dominant Compelling Helio-Ophthalmic Outburst) is a medical condition by which people exposed to bright light involuntarily sneeze. It has been suggested that the photic sneeze reflex occurs only after someone has been adapted to the dark for at least five minutes, although this is not certain, and is not uniform amongst people with the photic sneeze reflex. The condition occurs in one-sixth to one-quarter of humans, with more common occurrence in Caucasians than other human races. The trait is passed along genetically, with a 50 percent chance of inheritance.

http://en.wikipedia.org/wiki/Photic_sneeze_reflex