Annie Johnston and Chrissy Knott, two sisters from Ohio, made national news when they both gave birth to sets of twins on the same day at the same hospital. What's rarer than a set of sisters who also happen to have two sets of siblings who are perfect matches? That's so incredible it defies belief. However, the fact that the parents were sisters was not what shocked observers the most. Simply said, the biological father of these children was the same. What, then, was the backstory to this unbelievable occurrence? Let's take a look at the unbelievable reality of the situation.