My dad does. He was on my computer once, I think he was fixing something or borrowing it for some reason. Weeeell, he, being a parent, decided to do a little more exploring than was warranted at all, and I was pretty much helpless to do anything as I stood there and watched him navigate to my folder of "stuff..." He kind of gave me this raised eyebrow look at that point, and I remember panicking and spewing some kind of excuses, but I could tell he wasn't buying a bit of it, so I gave up and confessed. Fortunately, he was cool with it; he said that it was a little weird, but there was nothing wrong with it. He was actually more perturbed by the fact that I tried to lie about it (and the fact that when I did tell him about it, I was already super defensive. I think my exact words were, "Alright, so I've got a bit of a fetish. So-fucking-what.").
My mom, on the other hand, does not, to my knowledge, know. My dad promised he'd keep it to himself, but only if she didn't ask or find out for herself--he can keep a secret for me, but he simply will not lie to his wife. Which is reasonable. So unless she's pieced it together, she doesn't know, and if she does she hasn't said anything about it. There've been a few close calls, though. My dad, cool with it though he is, just cannot refrain from teasing me about it on occasion. I remember making some joke about masturbation while I was with my parents (yeah, we're that kind of a family), and dad made a joke about "tickling my fancy," and winked at me. I shot him the dirtiest glare I could muster, but my mom, fortunately, took it for just another euphemism for masturbation, so I dodged that bullet.