Celestial might work in conjunction with the "divinely favoured" feat. You are the chosen one of some god or other. Or, I may be misremembering, but I think I've seen unicorns on Krynn. As for the others, I might suggest the player refluffs or reconsiders. It would depend on how the DM felt about interlopers from other planes. If you are allowing portaling half orcs, then there is no reason not to allow genies arriving the same way. I consider creating characters for a campaign a cooperative activity, with a back-and-forth between the player and DM (instant messaging is great!).