Photic sneeze reflex (ACHOO)

The photic sneeze reflex (ACHOO) is the urge to sneeze when stepping into bright light. This variant is linked to how likely you are to have it.

Possible results

Likely a sun sneezer. You carry two copies of the version most linked to the photic sneeze reflex, the urge to sneeze when you step into bright sunlight. If you've ever sneezed walking out of a dark room into the sun, this may be why.

Maybe a sun sneezer. You carry one copy of the variant tied to the photic sneeze reflex (sneezing in bright light), so you may or may not be a light-triggered sneezer. It's a harmless quirk either way.

Unlikely to sun-sneeze. You don't carry the variant most tied to the photic sneeze reflex, so you're less likely to sneeze when stepping into bright light. It's a harmless trait that varies a lot between people.

Evidence & sources

Across global populations, about 21% of people carry two copies of this variant, and about 30% carry none.

This variant appears in 5 published genetic studies: PubMed 20585627 · PubMed 30617275 · PubMed 30899065 · PubMed 34446935 · PubMed 36477530.

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