April 29, 2010

Twins

Here's an interesting joint interview from The Believer with Steve and Mark O'Donnell, two identical twin writers who were the youngest children in a family of ten children. There's nothing flabbergasting in it, but if you want to hear two very witty and perceptive twins talk about being twins, this is it.

Steve O'Donnell invented The Top Ten List while David Letterman's headwriter, while Mark O'Donnell won a Tony for co-writing the Broadway musical Hairspray. Can you guess which one is straight and which one is gay?

Yes, you can.

By the way, using the Australian Twin Registry as a source, a survey by Northwestern University's J. Michael Bailey came up with a concordance rate of 22 percent for homosexuality among identical twins who were raised together, which is pretty low.

Also, Nancy L. Segal, one of main researchers of the famous "Minnesota Twins" project and author of the 1999 book Entwined Lives: Twins and What They Tell Us About Human Nature, told me that twins raised together rarely fall in love with the same person. 

This is interesting evidence for non-determinism in life's fundamentals.

27 comments:

adfadfadfa said...

How about some articles on thrins? I think that'd be more interesting than mere twins.

Anonymous said...

I understood from the research that the concordance figure was 22% for fraternal twins and 56% for identical twins?

http://www.nytimes.com/1991/12/17/science/gay-men-in-twin-study.html?pagewanted=1

Anonymous said...

For the past several years Ive privately hoped some nutrional studies would be conducted on twins to examine the effects of diet and excercise.

Twins would also be an ideal group to test various athletic training theories regarding speed and strength training.

Come to think of it, the psychological testing of twins in reaction to various stimili could also reveal much about us given the testing and control groups would be as similar to each other as possible, magnifying the conclusiveness of the results.


Steve's onto something here IMO.

Steve Sailer said...

Yes, but Bailey got to worrying about whether the methodology of Bailey's first study, which included advertising for twin subjects in the Chicago gay newspaper, would bias the results.

For example, say Wayne and Dwayne are both gay and are well known in the bars of Chicago's Boys Town. Then, some other gay might call the ad to their attention because he knows they are twins. But if only Wayne is gay and living in Boys Town, while Dwayne is a married golf pro in Dubuque, then fewer gays would know Wayne is a twin, so they'd be less likely to call Wayne's attention to the ad. Or various scenarios like that.

So, Bailey then used the Australian Twin Registry as an unbiased way to find twins, and only came up with a concordance in the low 20s. This was kind of surprising to him. He's about the most hardcore philosophical determinist I know. So, you have a whole bunch of pairs where nature and nurture are as similar as humanly possible, and, whoops, when one is gay, 78% or so of the time, the other is straight!

Average Joe said...

A piece on 60 Minutes a few years ago gave the impression that male homosexuality is caused in many cases by damage to the Y-chromosome that happens in the uterus.

Anonymous said...

Makes sense, thanks for pointing that out Steve.

However if there were a 'gay germ' as per the theory, would it not imply that concordance would be more prevalent in identical twins?

Occurs to me that testosterone could be one of the epigenetic influences. There is research that it is produced more by pregnant mothers under greater than normal stress. This higher testosterone is said to produce more sons also.

The most interesting comment of the piece was from Steve the straight twin , who wondered if Mark had got less fathering and attention from his older male siblings than he.

Whether this was a result of Mark not being receptive to male attention or the fact that the males in his family sensed that he was different is one of those interesting chicken/egg themes.

If the nature of the nurture, or the lack of nurture, is important in the etiology of gayness, there is very little research into the family dynamic pertaining to early development stages of gay children.

This seems to be a crucial aspect to the story....along with the mother's physical and emotional state during pregnancy.

SFG said...

I never bought this free will thing. If it doesn't come from environment or heredity, where does it come from?

frost said...

"This is interesting evidence for non-determinism in life's fundamentals."

I don't have any knowledge about how twins interact with the rest of the family but for normal siblings there is a great tendency for each child to find his own niche, to actively, if not consciously, move in a direction to differentiate himself from the others.

neil craig said...

It may tell us that falling in love is not the irresistable object romantics believe but something that involves a rational assesment of your chances. If the other twin has got in first what does the second twin have to offer unless they have won the lottery?

teacher.paris said...

Greg Cochran has suggested that male homosexualty might be a rare side-effect of some common childhood disease-not hereditary.

Anonymous said...

One of the women's fashion magazines--can't remember which one--recently had a feature on middle aged twins and how similarly they aged.

The ones who stayed away from the sun, didn't smoke, ate a healthy diet and exercised looked YEARS younger than their twins who did not. The ones who were 10-15 pounds heavier than their twins also looked much younger.

catperson said...

I'm not convinced that any gay has a straight identical twin. How do we know all thse straight identical twins are not just closeted homosexuals? What could possibly happen growing up that would make one twin gay while the other remains straight? Did one of the twins just happen to see an especially sexy photo of a same-sex person that the other twin missed? Or did one twin get more testosterone in the same womb that it shares with the other?

catperson said...

"Twins would also be an ideal group to test various athletic training theories regarding speed and strength training."

I would rather see studies that tested the IQ of identical twins raised together with vastly different levels of education (if such twins exist). This would show what impact, if any, getting more education has on IQ and g.

Anonymous said...

Greg Cochran has suggested that male homosexualty might be a rare side-effect of some common childhood disease-not hereditary.

Does being on the receiving end of molestation count as having suffered through a childhood "disease"?

It's certainly a "trauma", if nothing else.

Anonymous said...

I never bought this free will thing. If it doesn't come from environment or heredity, where does it come from?

Where, indeed?

The central question of our very existence.

Ray Sawhill said...

I know a couple of sets of twins where one guy's straight and the other's gay. I was under the impression that this was fairly common. Gay friends tell me they run across it fairly frequently anyway.

Joe said...

My wife went to school almost thirty years ago with a set of identical twins, one of who was obviously gay and the other just as straight. Both remain so to this day.

(I went to High School with a pair of fraternal twins, one of whom was a complete asshole and the other very nice and pleasant. So you never know.)

rob said...

catperson said...
I'm not convinced that any gay has a straight identical twin. How do we know all thse straight identical twins are not just closeted homosexuals?


How do we know everyone isn't a closeted gay? How do we know most gay dudes aren't just pretending to be gay so they get stuff from the gay billionaires who you think help other gay dudes out?

More seriously, family reaction to the first twin coming out might mediate whether the other twin does, if he is gay. If homosexuality is more concordant for twins from families that are accepting of the gay one than in less tolerant families, that might point towards closet cases reducing the concordance.

If a dude's gay, and his identical twin brother is too, why not at least tell him? Identical twins tend to be pretty close. With 56% concordance, about half of gay men with openly gay twin brothers would have to be closeted. I dunno if half of gay men are on the DL.

What could possibly happen growing up that would make one twin gay while the other remains straight?

A pathogen, getting hit on the head...science is for figuring stuff out.

MQ said...

People around here massively overemphasize the role of gentic determinism. The big effects of culture and environments are completely obvious if you simply drop your ideological blinders.

Also, there is no problem coming up with a Darwinian explanation for homosexuality, that notion that it's a disease or infection was one of the few genuinely dumb things Cochran ever came up with.

catperson said...

"If a dude's gay, and his identical twin brother is too, why not at least tell him?"

Because maybe you're so ashamed that you don't want to even admit it to yourself, let alone anyone else. And even if you did admit it to your identical twin, you may still hide it from the researcher doing the study on the herritability of homosexuality. I would expect that gay men would be much more ashamed than gay women (because the stigma of being gay is much worse for men) so I would predict that the concordance is higher for women. On the other hand female sexuality seems more fluid, so the corcodance for women might be less.

In any event, to really research this subject, you can't rely on self-reported sexual orientation and categories as simplistic as gay or straight. You need to actually measure sexuality on a continuous scale (like IQ) using sensetive tests of physical arousal in response to photographs. If you did this with identical twins raised apart you would find that homosexuality has a herritability of about 0.8 and that it increases with age as the effect of familiy environment gradually diminishes to zero.

Anonymous said...

I find it impossible to believe that a twin would not know/intuit that his/her sibling is gay.

rob said...

If you did this with identical twins raised apart you would find that homosexuality has a herritability of about 0.8 and that it increases with age as the effect of familiy environment gradually diminishes to zero.

Cite?

.8? So your already convinced that some homosexual men have straight identical twins.

catperson said...

rob, I don't have a citation, because the study I've described has not been done. I'm just speculating. And I'm not sure if 0.8 would imply that some gays have straight identical twins (except in extreme cases caused by unequal exposure to prenatal testosterone), but rather that not all gay twins are equally gay. It would be interesting to know the herritability of 2D:4D ratios.

gcochran said...

"few genuinely dumb things Cochran ever came up with."

Bill Hamilton thought it made sense. He knew a thing or two.
Possibly even more than you.

Anonymous said...

I went to business school with twins, one who was straight and the other gay. It was a bit embarrassing to a girl that the gay one was "dating" at the time (she was pretty hot too).

I think that this might be evidence for non-genetic determinism in sexual orientation, but it doesn't avoid the possibility that there might be something genetic that makes it more likely for you to be homosexual, as opposed to something genetic that makes it certain you will be homosexual.

Anonymous said...

Researchers tend to under-estimate the number of children produced by gay men, whether out or closeted.

Three gay men at dinner last night, with a total of 8 children between them.
All were gay-uncles also.

I think in the past these men were primarily shamans.

TGGP said...

MQ, could you give us a sketch of that Darwinian explanation?