Remember when you found out Santa wasn't real, or when you were old enough to realize just how implausible it is for a reindeer to fly? Well, there's more: Mistletoe isn't exactly the romantic symbol of the holidays that you think it is. Perhaps you already knew this. But if you didn't (or if you missed writer Robb Dunn's in-depth report on the evolution of the Christmas tradition), here's the gist: While there are historical explanations for why humans tend to kiss under mistletoe—a history of gods, demons, luck and a little lust—the evolutionary story of these plants with their sticky fruits and parasitic ways is more interesting.