There's a reason nerdy preteen Dustin Henderson doesn't have any front teeth in seasons one and three of 'Stranger Things.'
According to CNN, it's because actor who plays him, Gaten Matarazzo III, has a rare bone condition.
He was born with cleidocranial dysplasia, or CCD, a rare disorder which primarily affects growth of teeth and collarbones.
Like many celebrities, Matarazzo is using his new fame to bring attention to the condition.
Each season of the Netflix megahit brought an unexpected increase in weekly Google search traffic for CCD.
That's well above typical levels.
In fact, one CCD-related information page got 10,000 visits the week after the third season premiere of "Stranger Things" last summer!