On-screen couples often morph into real-life celebrity pairings. There’s Penn Badgley and Blake Lively of “Gossip Girl,” Angelina Jolie and Brad Pitt post-”Mr. And Mrs. Smith,” and, of course, Kristen Stewart and Robert Pattinson. Well, maybe.

But it kinda grosses me out when actors play relatives onscreen, and then end up getting down and dirty behind the scenes. Case in point: Lauren Graham (formerly of “Gilmore Girls”) and Peter Krause (formerly of “Six Feet Under”). While we think the pairing is adorable, we’re a little disturbed since they now play brother and sister on the show “Parenthood.” Lauren says it took a while for them to announce their couplehood for this reason. She says, “I’ve also been really protective of it, because it’s important that you can buy us as brother and sister on the show.” [People]

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