I have, but that's actually very common in royalty. I dont know how much it happens these days, but it was extensively common in the 'olden days'. Royalty believed they were of a special breed, and hence they didn't want to marry anyone 'beneath' them. Usually they married a cousin or distant relative to keep the bloodline pure.
LoL...yeah, I'm very aware of that, but I still find it icky.

Icky...yeah, thats the word I've been looking for.