Every time I feel like I have to sneeze but I just can't seem to get it out, I always look up at a light because I've always heard that this helps trigger the sneeze. Sometimes, this trick works like a charm, but other times I still can't seem to get the sneeze out of me. I've always wondered is it just a coincidence that this works for some people, or is there science behind this theory? After doing some research, I found that this is actually a genetic trait known as photic sneeze reflex. Although experts still can't fully explain this reflex, most agree that it is due to crossed wires in the brain. The trigemal nerve in the brain, which controls facial sensations and motor control, is located really close to the optical nerve in the brain. When light enters the eye, some of the electrical signal that is sent to the optical nerve to make the pupils smaller is sensed by the trigemal nerve, causing the person's nose to feel irritated, and therefore causing them to sneeze. There has not been very much research done on this reflex, but scientists have found that this genetic trait is found in about 10 to 35 % of the population. A study done in the 1960s proved that gene that causes this reflex is autosomal dominant, meaning if one of your parents has it, there is a 50% chance that you have it as well.