The Intelligence Paradox: Why the Intelligent Choice Isn't Always the Smart One - Satoshi Kanazawa 2012
What Does It Mean to Be Homosexual?
Why Homosexuals Are More Intelligent than Heterosexuals
Recall the discussion of the naturalistic and moralistic fallacies in Chapter 1. Science is all about what is, and it is never about what ought to be. Nothing in science is good or bad; everything just is (or isn’t). Science does not make any moral judgments.
Even though some form of homosexuality is observed in many species,1 the basic biological design of all mammalian species is heterosexual reproduction, and exclusive or predominant homosexuality is rare in nature. Most importantly, we are not descended from ancestors who were exclusively homosexual, so it is unlikely that homosexuality has been part of human nature throughout evolutionary history. In this narrow sense, being homosexual is unnatural; humans (as all the other species) are not designed to be homosexual.
So the Intelligence Paradox would predict that more intelligent individuals may be more likely to be homosexual than less intelligent individuals. But before we discuss the potential effect of general intelligence on sexual behavior, let's first of all talk about what it means to be homosexual or heterosexual. It's not as straightforward as you may think at first.
What Does It Mean to Be Homosexual?
Heritability of male homosexuality—the proportion of the variance in male sexual orientation that is explained by genetic factors—has been estimated to be between .262 and .60.3 So somewhere between a quarter and two-thirds of the variance in male sexual orientation is genetically determined. The remaining variance, however, appears to be accounted for by prenatal exposure to androgen in the womb; the more androgen—male hormones—the male fetus is exposed to in the womb during gestation, the more likely they are to become homosexual.4 This is why, for example, men who have more older brothers are more likely to be homosexual.5 Each additional brother increases the odds that a man becomes homosexual by 33—38%. The current consensus among sex researchers is that, between genes and prenatal hormones, men's sexual orientation is largely determined before birth,6 while women's sexual orientation is more malleable and fluid.7
There are four different measures of sexual orientation:8
1. Self-identified labels = whether you consider yourself to be homosexual, bisexual, heterosexual, etc.
2. Actual sexual behavior = with whom you have sex.
3. Self-reported sexual feelings = to whom you are sexually attracted and about whom you have sexual fantasies.
4. Genital or brain responses = physiologically measured arousal to male or female images.
In their 2005 book Born Gay, the sex researchers Glenn Wilson and Qazi Rahman note that self-identified labels can be influenced by political and cultural climate. For example, many homosexuals throughout history and in some oppressive regimes today have been forced to remain in the closest due to social pressure and threat of legal punishment, including death. Actual sexual behavior, Wilson and Rahman note, can be influenced by opportunities and circumstances. For example, many heterosexual men often have sex with other men while in prison due to the complete absence of potential female sexual partners.
In contrast, sexual feelings and physiological measures (3 and 4 above) are more stable and closer to individuals’ “true” sexual orientation. For example, self-identified heterosexual men who are openly and publicly homophobic may nonetheless show genital response of arousal to sexual images of other men.9 (Yes, some of the most openly homophobic men turn out to be secretly homosexual themselves. Remember the ex-Marine neighbor of Kevin Spacey's character in American Beauty?) Wilson and Rahman also note that homosexual fantasies are quite common in heterosexual men and women as a form of “mental explorations”10 and that measuring homosexuality with reported sexual fantasies and desires assumes that survey respondents are completely honest about them.
All in all, Wilson and Rahman conclude that physiologically measured arousal (genital or brain responses to sexual images of men or women) is probably the most accurate measure of true sexual orientation, and the other three measures may correlate poorly with it and may deviate from their true sexual orientation, especially among women.11
Given that an individual's true sexual orientation, at least for men, is prenatally determined (either genetically at the moment of conception or through prenatal exposure to androgen during gestation prior to birth), it is not likely that more intelligent individuals are more likely to be truly homosexual. There is a possibility, however, that the (as yet undiscovered) genes for intelligence are somehow linked to the (as yet undiscovered) genes for homosexuality in men, because genes for both intelligence and male homosexuality appear to be located on the chromosome Xq28.12 At any rate, given that the first three measures of sexual orientation (1, 2, and 3 above) are more malleable and subject to conscious choice and self-presentation, it may also be possible that more intelligent individuals are more likely to appear homosexual by these measures, that is, if homosexual identity and behavior are evolutionarily novel. Regardless of their true sexual orientation, more intelligent individuals may identify themselves as homosexual, engage in homosexual behavior, or report homosexual fantasies and desires.