Why are so many girls lesbian or bisexual?

You've probably heard about Constance McMillen by now. She's the openly-gay high school senior who wanted to take her girlfriend to the high school prom at Itawamba High School in northern Mississippi. The principal told the girls that all prom couples have to be boy-girl. Ms. McMillen called the ACLU, which threatened the school with legal action. In response, the school board canceled the prom. The ACLU then asked U.S. District Court Judge Glen Davidson to intervene and reinstate the prom. The judge ruled that although the school had violated Ms. McMillen's civil rights, he wouldn't force them to hold a prom. On Friday, April 2, Ms. McMillen attended an alternative prom at the Fulton County Country Club. According to the Associated Press, her girlfriend's parents wouldn't allow the 16-year-old girlfriend to go, so McMillen escorted another young woman instead. To make the story even worse, it turns out that the alternative prom at the Fulton County Country Club was a fake, with only seven kids attending, according to McMillen. The real prom, i.e. the prom which most of the seniors attended, was held at a still-undisclosed location, and McMillen wasn't invited.
The story continues to attract national attention because it's just so darn quaint. Imagine: there are still people who get upset when they see girls kissing other girls! Who knew?

Psychologist John Buss estimates that for most of human history, perhaps 2% of women have been lesbian or bisexual (see note 1, below). Not any more. Recent surveys of teenage girls and young women find that roughly 15% of young females today self-identify as lesbian or bisexual, compared with about 5% of young males who identify as gay or bisexual (see note 2, below).

As a physician and a psychologist, what I found missing in the noise surrounding the Constance McMillen story was any serious discussion of why a growing number of girls self-identify as lesbian or bisexual. Not that there's anything wrong with that, as Seinfeld might say. But why are young women today at least three times more likely than their brothers to identify as bisexual or homosexual? "I kissed a girl and I liked it," Katy Perry told us in her #1 hit single. Megan Fox, Lindsay Lohan, Lady Gaga, Anna Paquin, Angelina Jolie, Drew Barrymore - they all want us to know that they are bisexual. There is no comparable crowd of young male celebrities rushing to assure us that they go both ways. Imagine a young man singing "I kissed a boy and I liked it." Would that song reach #1 on the charts? Why not?

Why is it OK for girls to be bisexual or homosexual, but not boys?

Over the past seven years, I've posed this question to hundreds of teenagers and young adults across the United States. The most common answer I get isn't really an answer. "Girls kiss other girls at parties because guys like it," one teenage girl told me. "It makes the guys hoot and holler, so the girls do it again. They're just doing it for attention. It's not for real."

I point out, as gently as I can, that that response doesn't answer my question. Pretending to be lesbian or bisexual doesn't explain why a growing proportion of young women are lesbian or bisexual.

Or does it?

Female sexuality is different from male sexuality. If a straight boy kissed another boy, perhaps to amuse some girls who might be watching, he would be unlikely to undergo a change in sexual orientation as a result. But, as Professor Roy Baumeister at Florida State University and others have shown, sexual attraction in many women seems to be more malleable (see note 3 below). If a teenage girl kisses another teenage girl, for whatever reason, and she finds that she likes it - then things can happen, and things can change. If a young woman finds her soulmate, and her soulmate happens to be female, then she may begin to experience feelings she's never felt before.

Especially if all the guys she knows are losers.

Which brings me to the second point I've encountered in my interviews with young people. Twenty years ago, when I opened my practice in a suburb of Washington DC, it was rare to find 14-year-old boys who were looking at pornography every day. Today it's common, in fact it's becoming the norm. When I meet with a group of 14-year-old boys and I ask them, "how many of you guys subscribe to a porn site?", all hands go up. I don't believe them. But today, no boy wants to admit that he's the weirdo who doesn't look at online porn. Twenty years ago, hardcore pornography was tucked away in adult bookstores. Today any 14-year-old can access such photos online in seconds. Role models for young men, from pop singer John Mayer to the 2009 World Series MVP Hideki Matsui, talk openly about their collections of porn (see note 4, below).
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