According to the Journal of Adolescent Health, rising rates of anal sex among teens is reflected in the general adult population where anal sex rates have doubled since 1995.
"Somewhere around 2004-2005 an overused, initially funny and hard-to-attribute quote proclaimed that 'anal sex is the new black,'" wrote sexuality educator Cory Silverberg on About.com.
Anal sex statistics indicate that a generational change has occurred, where people born in the 1980s and later may be more comfortable admitting to or showing interest in anal sex. Silverberg attributes interest in the behavior among heterosexuals, in part, to the proliferation of pornography in the 1990s.
"I have been having sex for only 12 years, so I don't know if it was just something I didn't talk about when younger," said Tracie Egan, 29, who writes about sex and pop culture for Jezebel.com.
As with other sex trends, girls are more open to experimentation because pornography has become so easily accessible on Web sites like XTube and YouPorn, she said.
"Porn makes people more adventurous with their sex acts," Egan said. "Anal sex is sort of always considered the last frontier, pushing the envelope."
Raised in the 1990s, Egan was exposed to sex-laden MTV, documentaries on gay lifestyles and television shows like "Sex and the City."
"We were raised in a different way," she said. Girls of her generation, the so-called third wave of feminism, she said, were able to have sex with multiple partners and could detach themselves "socially and emotionally."
Still, Egan said that when she had anal sex with a boyfriend for the first time at 26, she was drunk, used no condom -- they were monogamous -- and didn't even know how to clean herself.
"Lack of sex education in school is really bothersome to me," she said. "Even I don't know about a lot of the biological issues."
Columbia's Kuriansky, author of "Generation Sex," has been hearing questions about anal sex from her college students for at least a decade. "Is anything wrong with having anal sex?" is the most common one.
"No," she tells them. "Except if you're forced into it or can't enjoy sex any other way."
Another question she often hears is: "If I want it, or like it, does it mean I'm gay?"
"Not necessarily," she answers.
What's changed in this decade is girls are now expressing an interest. "On college campuses it's escalated," Kuriansky said. "There's more talk, more books, more videos."
One speaker on the college circuit -- Tristan Taormino, author of "The Ultimate Guide to Anal Sex for Women" -- is gaining new ground with young women.
But, Kuriansky said, with fewer educational media outlets and less sex education, young girls are clueless about hygiene, possible bladder or vaginal infections and life-threatening diseases like AIDS.
"We are more open, but there's less information," Kuriansky said. "There are real myths and real efforts to be cool and people running around saying how great it is."
"But it's not just rubbing elbows," she said. "Anal sex is a serious public problem."