Fuck Anything That Flies: Bisexuality, Fruit Flies, And The Causes Of Sexual Orientation

This piece was originally published on the Blowfish Blog.

I love science.

From the vaunted Pharyngula science blog comes this hilarious and enlightening news of mutant bisexual fruit flies.

(As they say on Mythbusters: "Warning: Science Content." Lots of it, if you read the whole linked story.)

The gist, in case you don’t feel like reading all the darned neuroscience: In a particular species of fly, there is an occasional genetic variation -- I'm trying not to call it a mutation, that's such a judgmental word -- that causes them to behave bisexually. It causes some females to try to initiate sex with other females; it causes some males to wait for other males to initiate courtship; and it causes some males to attempt, equally, to initiate courtship with both females and males.

They will, to be blunt, fuck anything that flies.

And researchers haven't just identified the existence of the mutation -- excuse me, the variation. They haven't just identified the gene that causes it, even. They've identified the specific neurological mechanism.

(Hence the science content.)

Now, PZ Myers, Pharyngula blogger of song and story, warns that we shouldn't jump to conclusions about what this might mean for human sexuality. And I think he's right to do so. Human beings are rather more complex than fruit flies. And our sexuality is, to put it mildly, a lot more complex. Fruit flies don't, for instance, get hot for spanking, for latex, for women in seamed stockings, for men in seamed stockings, for bits and saddles, for stuffed animals, for cartoon characters, for curly-haired brunettes who look like Bette Davis.

So the fact that sexual orientation is genetically determined in fruit flies doesn't prove, even a little bit, that it's genetically determined in humans.

But it does tell us something about humans, and human sexuality.

It doesn't tell us that our sexual orientation is genetically determined, or even genetically influenced.

But it tells us that it might be.

It tells us that it's not ridiculous to consider the possibility.

It tells us that, at least in some animals, a tendency towards heterosexuality or bisexuality -- and arguably homosexuality, if you think about those male flies waiting coyly for the other male flies to make the first move -- is genetically determined. Entirely, as far as anyone can tell. And therefore, it tells us that it's not out of the question to think that it might be genetically determined -- at least partially -- in other animals as well.

Including humans.

And this is an important message: not just for the homophobic right wing, but for the queer-theory crowd as well.

There are queer theorists and activists who would be delighted to learn that sexual orientation is genetically determined at birth. For no other reason, they think it makes the civil rights battle easier to fight if they can play the "We were born this way" card. There are queer theorists and activists who think, not only that we might be born queer, but that we definitely are, and that the case is closed.

And there are queer theorists and activists who would be appalled to learn that orientation is determined by genetics. Even partially determined by genetics. Even a little bit determined by genetics. There are queer theorists and activists who actively resist this idea, who see it as dangerous and oppressive. There are queer theorists and activists who not only disagree with this theory, but who think that we should not even be considering it.

But here's the thing.

We shouldn't be thinking about this question on the basis of which answer we would like to be true.

We should be thinking about this question on the basis of which answer is true. We should be thinking about this question on the basis of which answer is supported by the evidence.

The question, "Is (X) behavior learned, genetically determined, or a combination of both -- and if a combination, how much of each, and how do they work together?"... this is, at least in theory, a question that can be answered. When it comes to human sexuality, it's probably beyond our current grasp... but that doesn't mean it always will be. It's probably going to wind up having an unbelievably complicated answer, but it's not the kind of question that inherently can't be answered with evidence and the scientific method. It's actually exactly the kind of question that the scientific method was designed to answer.

In fact, we're already beginning to gather some non-trivial data on this subject. And while the science is still in its infancy, or at least in its childhood, the current evidence seems to be leaning in the direction of "some combination of both." When it comes to human sexual orientation, genetics, at the very least, probably plays a significant role.


My inner twenty-something queer-theory constructionist is cringing at this. When I came out and started becoming active in the queer community, constructionism ("it's learned") was all the rage, and essentialism ("it's inborn") was seen as rigid and confining. It's been hard for me to accept the idea that sexual orientation may not, in fact, be entirely a product of a patriarchal society.

But my inner twenty-something queer-theory constructionist needs to get over it. The question of whether sexual orientation is born, learned, or both -- and if both, how and how much -- is not a question of opinion. It is not a question of politics or philosophy. And while there will almost certainly be ethical implications in the answer, it's not a question that should be answered based on which answer we think is morally right or wrong.

It's not a matter of opinion. It's a matter of reality. And I think that's how we should be looking at it.

Because no good -- politically, ethically, philosophically, or any other way -- has ever come from the denial of reality.

Comments

[Bob Airhart]

The cultural and physical changes taking place in our era may be more complex and profound than any other in human history. Thank you for reminding me to seek out the building blocks of reality instead of seeking bricks that appear to support my preferred construct of reality.

[Buffy]

While cultural factors may come into play to some extent, the fact that homosexuality and bisexuality are seen in so many species besides humans leads me to the conclusion that it is largely an inborn trait. After all, fruit flies, Bonobos and penguins aren't victims of bad parenting and Hollywood too, are they?

My greatest fear in finding "the gay gene" or any other definitive genetic basis for homosexuality is the obvious: the homophobes--even those who have been staunchly antichoice--will do an about face and decide that they'll make an exception for any fetus found to be gay. That will be, of course, a temporary measure while they search for a "cure" that can be utilized not only on currently living gay and bisexual people, but even to prevent future LGBTs.

Of course maybe I've just been reading too many RRRW sites and dystopian literature....

[lunalelle]

I guess my biggest problem with the essentialist viewpoint is that it's incredibly limiting. It disregards any number of queer experiences, including people whose sexual orientation changes over time. Basically, it's saying that you're born a certain way, and that's it. But even if there is a sexual orientation gene, there's no way to guarantee that the gene will be followed to the letter. People make decisions all the time contrary to their genetics. From an alarmist's standpoint, a gay gene might also lead to medication that can interfere with it.

Then there's the possibility that, like most things, some people are one way because of a genetic predisposition to be that way, and others are some way because of a more social constructivist creation. I hate to make a mental disorder analogy because I know as well as anyone that alternative orientations aren't mental disorders, but it's what I know: some people are genetically predisposed toward major depression. Other people experience life changes or trauma that leads to major depression.

I think it's ridiculous and limiting to play an either/or scenario. Embrace both essentialism and constructivism, have them both hate you, and feel like you're on top of things. :)

[Greta Christina]

I'm not arguing that genetics aren't a factor. I'm just arguing that, in humans, they probably aren't the sole factor.

The best single piece of research I've seen to support this is twin studies. Identical twins are significantly more likely to have the same sexual orientation as fraternal twins... but even in identical twins, it's not a 100% match. If it were entirely genetic, identical twins would have the same orientation 100% of the time.

And I totally agree with you about the creepy eugenics possibilities of a "gay gene." But again, I don't think we should be looking at this question in terms of what we would like the answer to be. I do think it's interesting, though, that the "it's genetic" argument can be framed as supporting gay rights or being a threat to them...

[M Dorian]

GC, your assessment of this profound and socio-culturally explosive topic about sexuality and genetic determinism was extremely well handled. I've long thought genetic factors go far in explaining a lot of human behavior. Of course our environment and social climate help mold us, but I'd bet many (even most) gay people would tell you they've known they were gay long before the pressures of "social conditioning" played upon them. In any case, GC, I think you wrote remarkably well on the subject.

(as for the identical twins studies, maybe a gay twin here or there doesn't want to admit to being gay. people lie a lot, and until there's a clear genetic marker, the jury's pretty much still out.)

[lunalelle]

@ MDorian:

Part of the reason why I don't think that the genetic theory holds water for the entire span of alternative sexual beings is because I'm one of those people who didn't follow the typical script of knowing I was gay all my life. I never had a sense that I was different sexually or in a gendered way. In fact, realizing I was gay two years ago came as a serious shock!

The idea of shifting sexuality breaks beyond essentialist barriers, and it leaves those of us whose sexuality does shift or breaks apart from alternative norms out in the cold.

It also discredits the people who do choose their sexual orientation.

[faux_pseudo]

I have long wondered why people think that orientation can't have any biological cause can easily accept that there are plenty of people in the world that are born with mixed sexual organs. For them to accept the existence of hermaphrodites (a massive and physical change from the norm) but not accept a small brain difference could cause homosexuality has always baffled me.

[Kagehi]

If it were entirely genetic, identical twins would have the same orientation 100% of the time.

Actually, Greta, you are dead wrong. Everyone has two sets of genes, while **some** can be dominant, and *tend* to be turned on, instead of the alternate, even those may not be in some cases. As a rule, if you had a gene like:

G-S

where G is gay, and S is straight, (its bound to be far more complex than that), then you have a 50-50 chance, unless one of "dominate" of having either the G or the S active, but you ***cannot*** have both genes, on both strands, from different parents active at the same time. Its one or the other, not both.

This is why you can get twins where one dies of a horrible genetic disease, while the other never shows any symptoms. While 90% of all their genes may have had dominate characteristics, which meant they activated identically between them, they was some 10% or so, which included the disease gene, which didn't activate the same way at all.

So, there is absolutely no reason for someone that has a gene that codes for being attracted to the same sex to *necessarily* express the gene at all, even if it is there. For them, even if they are a twin, it may, depending on when the split that produced the twin took place, simply be dormant in "that" individual.

Now, how likely it is that it would be active.. Depends on the gene, some may be pure 50-50, other may have dominate traits, which makes the odds 70-30 in favor of the gay, or the straight, gene. Its even possible that the trait, if complex enough, could be a chain reaction type effect, i.e., "if gene A activates, its makes it more likely that B does, instead of C, but if C activates, that makes it twice as likely that E will, instead of D, if D does, then S *must* be activated, but if E does, then the odds are 99.9% that G will be, instead of S, unless some random factor causes S to be instead anyway."

In other words, the odds of ending up gay may be linked to a whole series of genetic activations, which effect other transcriptions, which in turn determine the odds of still other genes being "picked", when they are made to go active.

Note, this is actually backwards, since in fact, at an early stage "all" genes go active, then some are refolded to "deactivate" them. But, for sake of simplicity, the above is a fair explanation of what could happen. It would also explain why you can get a wide range of "levels" of gayness. Linked developmental transcription factor may each increase the degree of disattraction to opposite sex, and the attraction to the same, with the result that only the right set of genes and activations/deactivations would produce someone 100% on *either* end of the spectrum.

After all, in such a scenario, its damned unlikely that every straight person has the same 5-10+ genes that code for being straight, or that every gay person would have the same 5-10+ that code for that. Most people, if 100% either way meant, for argument sake, having all 10 of the set, *most* people are probably going to have 4-6 that are one way or the other, since for them, cultural effects are far more likely to result in the passing on of that odd mix, than of its elimination by either extreme.

[Greta Christina]

Kagehi:

Well, shut my mouth. I didn't know that. Okay, I stand corrected.

I still stand by my main point: which is that the current science -- as understood by people who are actually experts in it -- supports a "partly genetic, partly environmental" hypothesis for the causes of sexual orientation. But I was obviously mistaken about the twin studies. Sorry about that.

[Kagehi]

Well, its a fairly recent discovery. Fact is, until a few odd cases popped up in recent years and someone both a) thought, "Why would one get the disease, but not the other?", and b) had the tools to find out which genes *are* active, it was thought that they where identical in every respect, that diseases where caused by external factors (some where not known to be genetic anyway), and that it wasn't possible for different genes to be active in one than the other. Small differences, like eye color oddities, slight differences in skin shade, etc., that where observed and discounted, should have clued the in that someone else was going on, but also got ignored in favor of other explanations. It was having known inheritable genetic diseases pop up in one, but not the other, than resulting in them taking a closer look and realizing it wasn't *quite* as clear as they thought it should be.

[Greta Christina]

lunalelle:

I agree with you about essentialism -- at least 100% essentialism -- not being right. But I don't agree with your reasons.

The problem isn't that it's limiting, or that it might lead to medication that can interfere with it, or that it discredits people. And it's not necessarily the case that genetics can't explain shifting orientations; people might have a genetic predisposition toward an orientation that shifts.

The problem is that the current science -- admittedly in its early stages -- doesn't support it. The current science supports some combination of genetics and environment (or essentialism and constructionism). And the research is still coming in.

And that really is the point of my post. We shouldn't be trying to answer this question on the basis of which answer we find most politically useful, or most personally preferable. We should be trying to answer it on the basis of which answer is most likely to be true; which answer is supported by the evidence. If we don't, we're no better than creationists.

[Valhar2000]

Greta, when you talk about "queer theory constructionists", do mean the sort of people featured in stories I've heard about, where a guy propositions some other guy and, upon being told that the propositioned guy is not gay, start going about how "everyone is bisexual" and "you're just lying to yourself"?

Are there people like that, or is it one more of the valiant efforts to "fight the Gay Agenda"?

[Ben]

The current issue of Scientific America has an article about identical twins and genes. It's not just that one twin may have a gene that isn't "turned on."

It's that identical twins aren't. Identical, that is. They don't have the same genome. We used to think they did. They don't.

[greensmile]

Thanks for the link, Greta. It took me weeks to put that info together and I am glad it continues to shed a little light where most people want to blow out the candles and close the curtains.

[Thomas Chong]

Lesbians are freaks of nature.

[Rebecca]

Only the more interesting ones, Thomas.

[Edgerman58]

For what it's worth, I think that sexual orientation is both nature and nurture. Some combination of the two does seem to make sense. As for myself,I think I have always had a bisexual "tendency". Yet, women have certainly played the greater role in my life, and men less so. I have no "theories". I'm not a scientist; but I think that it's becomming clear that we are part of a very complex continuum, and that for the last 3 billion years, life has been evolving in a connected, but branching way. So why shouldn't sexuality have a complicated, and nuanced, manifestation? For example, I love my wife very much, but that does not preclude the fact that I (sometimes) find myself "attracted" to certain men! It doesn't render my feelings for her any less valid or important because I'm bi! If anything, this makes me treasure our life together even more. It also makes me realize that human sexuality is wonderfully faceted. Why shouldn't it be? We shouldn't be surprised that it is. It sure makes for a more varied and interesting world! I agree that science will, eventually, settle this question, in time.