It's safe to say that a large number of adults do, given that there is a market for adult diapers, urinary catheters, and medications for urinary incontinence. Now that I think of it, I'm not sure what factors go into being able to control one's bladder at night. I think that it's probably neurological more than anything, I know everyone thinks of it as somehow psychological but I pretty well doubt that when you think about it. I mean, you have to be sufficiently aware of your body, you have to be capable of waking up, and you have to keep pressure throughout. Those are physical and neurological things.
I'm guessing that if anyone did have bed wetting problems into adulthood, they wouldn't likely admit it, even on a social anxiety board. Yeah, I do know a few adults who wet the bed that I've worked with, but they are all developmentally disabled so it's kind of a different situation. :stu