The recent spike in erotic romance book sales may never have happened if it wasn't for a determined college student and single mother named Tina Engler. In 1997, Engler created the first erotic publishing house and with-in five years, went from being on welfare to running a multimillion-dollar company-Ellora's Cave.

With over a dozen subgenres-including a line expressly for men-the company caters to a variety of readers.

In honor of National Romance Month, the International Business Times sat down with Ellora's Cave CEO, Patty Marks, to learn more about the thriving company.

Would you say that Ellora's Cave is getting more attention than ever before?

Yes. We've been around for 12 years and doing well in that time. All of a sudden "Fifty Shades" brought about media attention. The e-book revolution has been a major part of that. Also, I think women finally feel allowed to celebrate their sexuality.

How has the erotic romance industry changed since the company began?

When Tina started Ellora's Cave, books weren't available digitally. She used PayPal to sell books and then would e-mail them in a PDF format. There were some e-reader precursors but they never took off. So I would have to say that technology revolutionized the industry.  

On average, how many books does Ellora's Cave sell each month?

We sell about 200,000 books per month and we have some authors that make six figures a month in royalties.

What have you found are you most popular subgenres?

BDSM (bondage, discipline, sadism, masochism) has always been a popular subgenre-even before "Fifty Shades." We've had that subgenre for a long time and we have some really good authors. Joey Hill for instance -- she has actually lived the lifestyle.

Stories that focus on vampires, werewolves, and anything else paranormal also tend to be very popular. Vampires have been a hit with readers since Anne Rice released "Interview with a Vampire." We've had a lot of success with fantasy stories-some involving aliens or an alternate species. Capture fantasy stories are also pretty big.

Would you say that fans of "Fifty Shades of Grey" enjoy books released by Ellora's Cave?

Our books are very explicit. "Fifty Shades" is actually quite tame when you compare it to other works of erotica. Books like Anne Rice's "Beauty" trilogy are more aligned with our work.

Overall, we do offer a variety of stories that appeal to many different readers. If we have a story that's more sensual-we add it to our Blush line. We also have a Romantica line for erotic romances and an Exodika line, which is straight up erotica.  

It's been argued that books like "Fifty Shades of Grey" can lead women to have unrealistic expectations in men. Do you think that's true?

I think that most women who read these books know that they're fantasy. It's an escape -- like watching a romantic comedy. It's not like most women believe that the plots of those movies will somehow happen to them.

"My Secret Garden" is an amazing feminist work that compiled sexual fantasies of real women. Some of them are incredibly shocking but they're derived from their imagination.

Tales of submission have been deemed misogynistic by some. What's your take on that?

What some people don't realize is that you have to have power in order to give it up. Women who are submissive in their everyday lives probably don't fantasize about the loss of control. Tales of submission have become more popular in the last few years because so much is expected of women. They want to someone to take over occasionally.

Does Ellora's Cave have any male writers?

We do have some. What's interesting is that the men tend to write more sensual stories versus those that are highly sexual.  We used to have a male college professor that wrote for us under a female name.

Male/Male (which focuses on a relationship between two men) books are typically written by heterosexual women. That started to become a popular subgenre after the release of "Brokeback Mountain" because that story had angst and emotion -- of course the fact that it had Jake Gyllenhaal and Health Ledger didn't hurt.

What types of stories do you absolutely not consider publishing?

Anything violent, anything involving bestiality or snuff. Stories involving anyone under eighteen years old.  

There was a "Fifty Shades" event in NYC a few weeks ago and a number of angry protesters mobbed the venue it was being held in. They handed out flyers claiming that the book is pornography and should be banned. It can be argued that the thought of women taking charge of their sexuality is hard for some to grasp.

It's interesting that there aren't more protests over the violence in the media. How many films show people dying as if it's nothing? What's so disturbing about two consenting adults having sex?

"The Dark Knight Rises," for instance, has some pretty unsettling scenes. (The interview took place prior to the Aurora, Colo., shooting.) But since the media often caters to what men find appealing, the violence seems to be acceptable.

That's true. The last few "Batman" movies were extremely dark but I don't remember anyone protesting that.

To learn more about Ellora's Cave, visit the company's official site.