Here's the gist of it: "The uncanny valley is a hypothesis that when robots and other fascimiles of humans look and act almost, but not entirely, like actual humans, it causes a response of revulsion among human observers."
Check out the link and prepare to get nauseous; Repliee Q2 is already making me woozy. Also, check the link I posted last night: one of the marionette scenes from Being John Malkovitch.
Some time ago we got comp tickets to Ronnie Burkett's show, Provenance. I couldn't go! Not long after I heard Ronnie talking on the radio about why he thought certain people were creeped out by marionettes, and he said he thought it had to do with the Catholic church, and its use of icons.
As weird as I think that sounds, I did in fact grow up Catholic. And get this, (I think Ronnie's obviously done his research), according to Wikipedia's entry on marionettes, "the Christian church used marionettes to perform morality plays." And the word "marionette" or "Mary doll" is associated with the Virgin Mary.
Anyway, I think it has a lot more to do with the uncanny valley than the Catholic church. For all it's many flaws, I've never gotten that creeped out by the statues in any church or cathedral. Except for the ones whose eyes follow me.