As noted above, as far as I am aware the methodologies of all genetic or otherwise biological (i.e., epigenetic) studies are premised on the assumption that human sexuality consists of two monosexual orientations--everyone is either gay or straight. I suspect that few of the researchers who employ such a methodology actually believe that this premise is true. Worse, this methodology uses, and I think ultimately promotes, the disease-model of same-sex sexuality--strict heterosexuality is assumed to be the norm, and any sort of same-sex attraction is the deviation for which a genetic difference is sought. This assumption of genetic heteronomativity is somehow maintained despite the unequivocal contrary evidence provided by other cultures as well as by our closest living relatives, among whom same-sex sexual activity is quite common. It is surely a satisfying notion to the “nuh-uh, no, never, not me, never looked at another [guy/woman] like that!” crowd.
In any case, using the premise of binary sexual orientation, it’s easy to understand how someone could find a genetic association (especially if a Bonferroni correction is not done) that would disappear if sexual orientation were assessed according to a range of possible categories, such as a Kinsey scale. If one classified a classroom of students as wearing either “dark” or “light” socks, one might find an association between sock “color” and grades, an association that would undoubtedly disappear if sock color were assessed according to range of colors.
But the assumption that sexual orientation is binary is worse than merely offensive in denying the existence of bisexuality and bisexuals--it’s illogical. After all, how does one explain these other cultures such as Melanesian societies where 95% of men (at least) engaged in sexual relationships with both sexes, or the commonplace same-sex relationships among the (usually married) free men of ancient Assyria, Greece and Rome? As my friend Kenji Yoshino discusses in “The Epistemic Contract of Bisexual Erasure,” there are powerful social, political and psychological motives to erase bisexuality: “Bisexuality is . . . threatening to all monosexuals because it makes it impossible to prove a monosexual identity.” http://kenjiyoshino.com/articles/epistemiccontract.pdf It isn’t difficult to understand why a bisexual might choose to limit his/her sexual activity to one gender or the other. On the other hand, except as a response to social pressure, it’s much more difficult, and ultimately impossible, to understand why someone who has zero sexual attraction toward people of one gender would go to the trouble of engaging in sexual activity with people of that gender. As long as bisexuals exist, anyone might be a bisexual, but some people simply do not express their sexuality in such a way. After all, there is nothing more common than declining to pursue sexual activity with someone--we all choose to not pursue sexual activity with someone every day.
In any case, using the premise of binary sexual orientation, it’s easy to understand how someone could find a genetic association (especially if a Bonferroni correction is not done) that would disappear if sexual orientation were assessed according to a range of possible categories, such as a Kinsey scale. If one classified a classroom of students as wearing either “dark” or “light” socks, one might find an association between sock “color” and grades, an association that would undoubtedly disappear if sock color were assessed according to range of colors.
But the assumption that sexual orientation is binary is worse than merely offensive in denying the existence of bisexuality and bisexuals--it’s illogical. After all, how does one explain these other cultures such as Melanesian societies where 95% of men (at least) engaged in sexual relationships with both sexes, or the commonplace same-sex relationships among the (usually married) free men of ancient Assyria, Greece and Rome? As my friend Kenji Yoshino discusses in “The Epistemic Contract of Bisexual Erasure,” there are powerful social, political and psychological motives to erase bisexuality: “Bisexuality is . . . threatening to all monosexuals because it makes it impossible to prove a monosexual identity.” http://kenjiyoshino.com/articles/epistemiccontract.pdf It isn’t difficult to understand why a bisexual might choose to limit his/her sexual activity to one gender or the other. On the other hand, except as a response to social pressure, it’s much more difficult, and ultimately impossible, to understand why someone who has zero sexual attraction toward people of one gender would go to the trouble of engaging in sexual activity with people of that gender. As long as bisexuals exist, anyone might be a bisexual, but some people simply do not express their sexuality in such a way. After all, there is nothing more common than declining to pursue sexual activity with someone--we all choose to not pursue sexual activity with someone every day.