Just a quick tidbit here for those of you who don't know:
Romance is 40% of the fiction market. By sales.
This is one of those things that makes me laugh at genres. How is romance a genre? Romance is a thing that happens in stories. People fall in love, fall out of love, etc. Obviously the romance "genre" specifies things a little, and you're always supposed to get your happy ending. They follow a formula, but then again so does most high fantasy.
Romance may once have been a strictly non-genre affair, but that has changed. especially since Twilight. There were plenty of paranormal and fantasy romances before Twilight, but it was Twilight that pushed paranormal romance into the heights it is experiencing today. Right now it's harder to find a show that doesn't have a paranormal fantasy bent to it. Vampires are being thrown into every possible form of entertainment possible, and vampires have always meant sex. Remember Dracula? The Bram Stoker one? That was a paranormal romance in a way -- it certainly had more sex in it than many other books at the time
Now though, we're getting incredible books like Cinder, about a cyborg Cinderella which is what kind of genre? It's not cyberpunk, really, because it's the story of Cinderella, modified. It's not really focused on the "against the man" attitude that the cyberpunk genre encapsulates. It's a fairy tale romance that has been turned sci-fi. And it is awesome. Steampunk romance books are nothing new, but are gaining further traction in the industry, and they rule too! Having trysts and dates and romance isn't the no-no that it once was -- that is to say, the market has realized that not only are there more than just straight white male readers of genre fiction but that straight white males also enjoy romance. Not as much as the ladies for now, but I'm willing to bet that that's just because of the dearth of male protagonists in non-gay romance novels.
Romance is not only something that should be in your books because real life has romance but additionally because romance is selling like hotcakes! The old ways are changing, and with moms everywhere falling back in love with erotica thanks to Fifty Shades of Grey (which actually isn't that erotic, it's just some standard BDSM), sex is something that I think we will start seeing much more of in genre books (scifi is long past this one). Which is great, because sex is something everyone has. How insane is it that something we all do, something we all love to do, is something we're so ashamed to talk about, and actually not allowed to talk about in some situations, by federal law!
"Little children might hear it"
Look, they're gonna hear it from the Discovery Channel anyways, so just let it happen, okay?
There's no reason you need to add sex and romance to your book like HBO and Showtime: unorganically and in great quantities. If your story doesn't include sex, or doesn't have room for romance, that is fine. But you shouldn't be scared of where your story goes if you find it going down hotter roads. If you set out writing an epic fantasy and it turns into a hot near-erotica romance with high fantasy trappings that is awesome. I was informed by a romance author at a recent con when I asked about an anthology of erotic sci-fi stories called Zero-G Sex that erotica is a fabulous way to get into the market right now.
But don't take my word for it, go out and see for yourself! If appropriate, put a little sex scene in your story where you would have left it blank. See what happens, and see who likes it. You may be surprised.