Causes
Dr. Mahmood Bhutta, an otorhinolaryngologist at John Radcliffe Hospital, states that sexually induced sneezing may be genetically determined, and may result from the way the central nervous system is wired:
"his reflex demonstrates evolutionary relics in the wiring of a part of the nervous system called the autonomic nervous system. This is the part beyond our control, and which controls things like our heart rate and the amount of light let in by our pupils. Sometimes the signals in this system get crossed, and I think this may be why some people sneeze when they think about sex."
Another possible explanation concerns the existence of erectile tissue in the nose, which may become engorged during sexual arousal, triggering a sneeze.
Read more about this topic: Sexually-induced Sneezing