A. Scientists assume that such sneezing patterns are genetic, but the issue has not been extensively studied, in large part because most sneezing is benign.

 A rare exception is the syndrome called intractable sneezing, which has usually been found in adolescent girls. Because these severe bouts of uncontrolled sneezing respond well to psychological therapy, it is also called psychogenic sneezing, though some researchers suspect it is not always psychological in origin.

One inherited kind of sneezing, photic sneezing, occurs upon sudden exposure to bright light. It has been given a catchy acronym, Achoo syndrome, derived from a longer term, autosomal dominant compelling helio-ophthalmic outburst.

Researchers theorize that photic sneezing results from crossed nervous pathways for the light-response reflex and the sneezing reflex. It has an autosomal-dominant inheritance pattern, meaning that the mutated gene that causes it is dominant and needs to appear on only one copy of an inherited pair of genes.

In this case, the sneezing pattern is predictable, at least within families, according to the geneticist and pediatrician Dr. Roberta A. Pagon, who with her colleagues coined the Achoo acronym in 1978. It is constant from episode to episode and typically numbers two or three.  

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