Some people are attracted to women; some are attracted to men. And some, if Sigmund Freud, Dr. Alfred Kinsey and millions of self-described bisexuals are to be believed, are drawn to both sexes.
But a new study casts doubt on whether true bisexuality exists, at least in men.
The study, by a team of psychologists in Chicago and Toronto, lends support to those who have long been skeptical that bisexuality is a distinct and stable sexual orientation.
People [this should say "men"] who claim bisexuality, according to these critics, are usually homosexual, but are ambivalent about their homosexuality or simply closeted. "You're either gay, straight or lying," as some gay men have put it.
In the new study, a team of psychologists directly measured genital arousal patterns in response to images of men and women. The psychologists found that men who identified themselves as bisexual were in fact exclusively aroused by either one sex or the other, usually by other men.
I'm not sure how convinced I am by this research, but, assuming it's true (which could be a big assumption), here's why it's important: As I pointed out to Bailey in about 1998, it suggests that, in terms of sexual orientation, males are distributed along a strange J-Shaped curve, with more homosexuals than bisexuals (and of course far more heterosexuals than either). In contrast, women seem to be distributed along the left half of a normal bell curve, with more bisexuals than homosexuals.
This suggests that male sexual orientation is more like a simple switch than a randomizing Pachinko machine, which is more common among complicated human traits, such as, apparently, female sexual orientation.
Here, Thrasymachus interviews Gregory Cochran about the implications of the J-shaped curve and why Greg thinks it would be a good idea to clone a gay sheep.
And here's my 2003 summary of the theories over the cause of male homosexuality, which remains one of the great mysteries in science.