Let him read it. If he's like most guys, he'll be put off when he realizes its just lovey-dovey chick-flick stuff. If he likes it, explain that あなた don't and if he's a mature parent, he'll understand and not be obsessive over it. At least not in front of you.
Does everybody have to do only what あなた say is okay?
It's okay for people to be diverse and to have different opinions than you. I personally think it's a good thing for people to like things. It's also okay for people to use their own minds and judgement and to determine for themselves what they like and do not like.
If he likes it, that would not make him a bad father. It wouldn't change him if he doesn't like it either. What 本 your mother likes shouldn't make much of a difference either.
Tell your dad the basic storyline of twilight and tell him your opinion on it. Then if he wants to read it let him, あなた can't stop others 読書 it... they've got to read it themselves and develop their own opinion.
Just let him read it and draw his own conclusions. He shouldn't run his life based on your opinions.
Seriously, just respect whatever he decides to do and whatever he thinks of the books.
Different opinions make the world go round, :P
How is this even a question? Isn't it a 与えられた that he should just be able to read whatever he wants?
Seriously. My parents and brother enjoy a lot of things that I don't. Like activities, books, music, etc. I can't stand a lot of the things they like, and I know they don't like some of the things I do, but we respect each others differences and try not to cram our own opinions down each others throats. It works. Really, it does, :)
Look, realistically I doubt your dad will be all obsessed over it. I'm sure he'll burn it before he's read the first chapter. Honestly, this shouldn't be much of a problem to you. So what if he wants to read it? So what if he likes it? It's not like he's going to infet the whole house with Twilight merchandise. (Trust me. Dads don't do that.) Love, Brijbee.