Who could forget that pivotal Sopranos episode when Ralph Cifaretto took a dildo up the butt from Janice Soprano? A few fans spoke out in disgust, decrying it as unnatural and howled in outrage that the show would support such "gay" acts.

There has been a growing trend of straight males who desire females to don on a dildo and give them a good plowing. Books like Jack Morin's Anal Pleasure & Health, The Ultimate Guide to Anal Sex for Men by Bill Brent and films like Bend Over Boyfriend and its sequel by Fatale Video are testaments to the rising popularity of men giving women rear-entry access and enjoying it.

Is it a homosexual act and is that where the stigma lies? Sociologists over time developed what is known as heteronormativity, or the hetero-normative model of gender and sexuality. It dictates that humans are either males or females and any behavior that deviates from "maleness" and "femaleness" is not normal. As a result, gender roles emerged, where every man and woman were expected to act a certain way. The gender roles allotted certain behavior patterns based on sex.

According to Charles Darwin and evolutionary biology, the reason why men and women have sex comes from their natural urges to procreate for the propagation of the species. It is also the reason why men tend to go for younger, healthy-looking women as they appear to have the strength to sustain childbirth and successfully reproduce. In resultant, evolutionary biology reinforces heteronormativity in that the need to breed justifies the reason why men and women have sex with each other and not with their own genders.

One can say the hetero-normative model normalizes heterosexuality. In the standpoint of evolutionary biology, homosexuality serves no purpose. Even further, anal sex, technically, has no real function in the propagation of the human race. Such logic has been used to create anti-sodomy laws, which are still intact in certain areas of the United States. So when fans of The Sopranos saw Ralph getting it from behind by a woman and dubbed it "unnatural," their exclamations were not new. Ralph was on his side in a submissive position with Janice Soprano poised behind him with a dildo in a moment of reversal of gender roles and in defiance to Darwinian principles.

What sort of man, who neither identifies himself as gay nor bisexual, enjoys anal sex? Ralph from The Sopranos is always described as a "made man," a high-ranking member of the mafia. Made men are essentially royalty in the underground circles they belong to. They have power, wealth, prestige and access to many beautiful women. Similarly, Timon, 33, a successful businessman/professor and an avid fan of women who are willing to strap on a dildo, say on the matter: "I love female domination. There's nothing hotter than a woman telling me I'm scum while fucking me up the ass."

So, why the urge to go against nature, so to speak, especially when nature is kind to these men? The famous psychoanalyst Sigmund Freud may have an answer. Freud was convinced who we are as adults depend heavily on our sexual experiences as a child. He mapped out what came to be known as the psychosexual stages of development. A failure to overcome certain obstacles during each stage causes children to develop "quirks" in their personalities as adults.

During the second stage of a child's life, incidentally named the anal stage, occurs between two to four years of age. In this stage, the child discovers the pleasure of defecating and the joys of bowel control, or the exercise of power. The child learns to hold on or let go. Delays in toilet training and problems with parents may cause the child to develop anal retentiveness later in life. A good indicator is the person's need to compulsively clean, a frantic desire for cleanliness as well as to control the environment surrounding them.

At this stage, the child is confronted with two kinds of impulses that are active and passive. There is the impulse of mastery (active) and the impulse of gazing (passive). The former may be prone to acts of cruelty later in adulthood. Theoretically, a man who never successfully got over the anal stage can easily fall into sexual fetishes, such as BDSM and female domination, according to Freud.

Inversely, how do women feel about strapping on a dildo and giving their male counterparts a love tap on the bum? Society and evolutionary biology say it's an uncharted territory and that's how it should remain. Yet, it takes two to tango and straight men need their women's help to fulfill this particular sex act.

Heteronormativity tends to bolster patriarchal values and places women at a lower standard than men based on their sex, i.e. they're physically weaker and it takes longer for them to reach an orgasm. Women doling out anal sex to men gives them an opportunity to reverse gender roles and blend gender lines, which have been increasingly blurred since the feminist movement of the 70s.

Kimberly, 23, a forensics student describes her first-time usage of a dildo on a man. "I was reluctant, at first. I didn't really get into it until he told me to call things out to him, like, 'Yeah, take that, bitch' and 'You're nothing but a loser.' I felt powerful and we both got off on it. Ever since that time, I've been hooked.'

Who really knows why certain people do the things they do? It could simply be we're no longer in an era where people solely needed sex for survival, i.e. mass reproduction. Humans are classified as Homo sapiens, or "knowing man" in Latin. They have a highly developed brain, which marks their high level of intelligence. As intelligent creatures, coupled that we're past the time when dinosaurs roamed the Earth and the fear of getting trampled on and wiping out an entire generation was real, other areas of our brain have been able to develop.

Humans have highly developed cerebral cortexes compared to other animals. The cerebral cortex is in charge of memory, language and most complex thinking processes. It is also in charge of the relaying of pleasure, including sex.

A woman strapping on a dildo and tapping a man's ass, or anal sex in general, may go beyond our needs to procreate. We may do it strictly for pleasure. If dolphins can have sex for pleasure, then humans certainly can.