Editor’s note: This post has been edited to reflect changes in our product.new genetic discovery that at least partially explains why some people sneeze when they go from darkness to light. A certain genetic variant increases the likelihood of having this photic sneeze reflex, also called the ACHOO syndrome (short for Autosomal-dominant Compelling Helio-Ophthalmic Outburst syndrome). Each copy of the C version of is associated with 1.3 times increased odds of having the trait in people with European ancestry.The reflex is harmless but understanding this common trait could help scientists better understand other light-triggered reactions, such as some types of epileptic seizures. This discovery was fueled by 23andMe customers who took the survey “Ten Things About You”.We hope you aren’t sneezing today, but if you are then perhaps you can blame it on your DNA. Either way 23andMe wishes all of you a happy summer solstice!