Kids are germ vectors. Seriously, it is a coincidence probably. The only thing I can think is kids touch everything and climb all over adults, so their germs are everywhere, but you said even when an adult sneezes on you, you never get sick, so it’s probably not that. Although, they once did a study of sick people and well people spending time in te same room, and sick peole and well people playing cards, and by a lot the card playing group caught the cold more often than just simply breathing in the “sick” air.