Have you looked at the elf family trees? Yowza! That's why they have pointy ears, not because they're elves but because they're so inbred!
Well, Arwen is actually Aragorn's great-great-great-something-aunt, isn't she? If Aragorn is directly descended from Elros...
Yep, she's his cousin many, many times removed because Elrond is his great, great, great.....uncle. Plus, Elrond and Celebrian are related to eachother in some convoluted fashion. I'm pretty sure Galadriel and Celeborn are too. It's so very, very complicated!
My theory was that Eomer didn't get out much, and just hung about Faramir and Eowyn's parties, till they set him up with Imrahil's daughter.
This is another reason why I should never write LOTR fanfic.
Yeah, I can totally see that.
FARAMIR: Darling, we've got to do something about your brother. He's drunk two bottles of Amroth wine *again*.
EOWYN: That's nothing. You should have seen him at the parties in Edoras when we were younger. *mimes tipsily riding a horse*
FARAMIR: Oh, that sort of thing, eh? Well, if it keeps him out of the medicine cabinet....
(EOMER stumbles into FARAMIR and spills the Steward's wine)
(LOTHIRIEL has been sitting bored on a sofa. She stands and passes them on her way to the chips)
EOMER (in a slurred Cockney accent, or the ME equivalent): Hey, now, I'd like to fill her saddlebags, if I'm not being too subtle.
EOWYN (used to this): You're not.
FARAMIR: She *is* single, wafflepumpkin.
EOWYN: *shrug* If it keeps him out of the medicine cabinet.
FARAMIR: *waves* Oy! Coz!
Am scanning in my Complete Guide to Middle Earth family trees for you. The incest and inbreeding is much more evident in them. :)