Not to mention we don't actually know how old Ann is. We know she's in high school, and that she's in George Michael's class, but that doesn't mean she isn't 18 -- GM could be young for his grade or Ann could be old, or both. And this wouldn't be the first time GOB dated someone in high school. And even if Ann isn't quite 18, is 17 really less moral? Less legal, maybe, but less moral? And since when has GOB cared about moral? Or legal? I'm not saying it isn't creepy ('cause it is) but I agree that any of the Bluths dating Lucille 2 is just as creepy. It certainly hasn't crossed the line, in my opinion. Especially since GOB made it clear that they haven't done anything illegal yet.
Eve Holt is also an interesting theory, though.