Well, my dad is just insane: we're talking about someone who's wordlessly watched me play Gears of War, then got disgusted when I was jumping on a turtle's head in Super Paper Mario because I was "hurting that guy." He also couldn't figure out where to go when we played Mario Kart.
My sister just doesn't bother. She's a farmer, and she thinks its weird that I enjoy them so much, and she seen no value in them whatsoever. Kind of annoying, really.
My mom's playing is limited to Peggle, but I've gotten her to understand the literary value behind gaming. I've gotten her interested in Final Fantasy X, but she can't handle the battle system. I really don't get how that can't be understood, especially since it's not the active-time system and you can take however long you want taking your turns... but whatever. I got her to see eye-to-eye on games as an artistic storytelling medium, so I'm happy.