There is a genetic trait called sun sneezing when sufferers from ACHOO syndrome sneeze uncontrollably when exposed to direct sun
light. The allele that causes sun sneezing is dominant over the non-sneezing allele. A sun-sneezing man marries a non-sneezing woman. They have many many children and all are sun sneezers. If they have a 23rd child, what are the chances that it will be a sun-sneezer? How do you know?
