[David Sklansky]

"Might it be that there were certain practices engaged in by the Jewish community that rendered their children immune to a disease that was killing off young non-Jewish Egyptians? Perhaps dietary restrictions? And perhaps whatever it was effected older children more than younger, thus giving rise to the first-born aspect of the story."

It supposedly all happened in one night. Any miracle has extremely farfetched explanations. At some point, if the miracle is true, Baye's Theorem says it is more reasonable to believe in God.