I never do fic recs. (I don't even know if there are interested people on my flist, really.)
But if you are a Phile, you must read
Machines of Freedom, by
amalnahurriyeh.
It has just shot to the top of my list of favorite fics. Seriously. It's colonization, post-IWTB, and involves kids - and I know one or several of these things might not generally be your XF cup o'tea, but Amal is a phenomenal writer and she handles it all deftly, and with a sense of humor and realism (as much as you can get from such a sci-fi premise) very true to the show. Also, she herself is a sci-fi geek, so if references to Doctor Who, BSG, Star Trek, Star Wars, The Matrix, and probably others make you grin like they do for me? Those are an extra bonus.
But the best thing, and the most important thing, is how real and right the characters feel - not just Mulder and Scully, but secondary characters we know and love, and grow to know and love.
It's long, but it's truly epic. Go read when you have the chance!