Saturday, January 31, 2009

Psychology Today - A Cartoon Guide to Sexual Orientation

Hilarious, and educational.

A cartoon guide to sexual orientation

Ever since we published the first genetic scan for male sexual orientation, one of the most frequent questions I get asked is "why are people gay." While I have done my best to share information about the science of sexual orientation (this blog being one example), I am not an animator so I haven't explored cartoons as an option. Fortunately, I don't have to now because a cartoon recently posted on YouTube does a fairly good job. The video tries to take on two of what I like to call "the big three arguments against gay people." If you listen to enough anti-gay rhetoric you will find it usually comes down to at least one of the following statements, "I don't believe in it, its unnatural, it's a choice." After discovering these beliefs to be the root of most anti-gay propaganda Watch the video and then let me fill in some of the details from research on sexual orientation.


The video starts out with theories about parental influences on sexual orientation, like having a distant father or overbearing mother making a man gay. In fact, this was a theory put forward by some Psychologists and Psychiatrists. It was also used to explain why some people were schizophrenic. Eventually it was disproved in both cases. For example, in the 1970 researchers at the Kinsey Institute conducted a large survey and found no support for the idea that these kinds of parental influences made children gay (Bell, Weinberg, & Hammersmith, 1981). In the 28 years since that book was published there hasn't been any credible evidence showing that any kind of parental behavior changes the sexual orientation of their children.

Being gay is natural.

Next the video tackles the question of if homosexuality is "natural." This is one of the big three. I don't believe something being "natural" is a good argument for or against it. After all, lead is natural, but that doesn't mean I want it in my drinking water. Nevertheless, the point made in the cartoon about animals is true. Many species of animals engage in same-sex behavior and some have members that exhibit primary sexual attractions to their own sex. A few very good books have addressed this topic (Bagemihl, 1999; Sommer & Vasey, 2006).

You don't decide who to love.

When Martha says "You don't just decide who to love," I think she is right. Research shows that sexual attractions emerge around the time of puberty. If you think back to puberty, do you remember making a choice of who you would be attracted to? In fact, research shows that it doesn't matter what your sexual orientation is, it tends to emerge around the time of puberty. All indications are that people don't choose their sexual orientation.

It's in our genes.

Twin research has indeed found that if one identical twin is gay the other twin is also more likely to be gay. More importantly from a scientific perspective, is the fact that identical twins are significantly more likely to have the same sexual orientation than fraternal twins (Mustanski, Chivers, & Bailey, 2002). One of the best of these studies found the heritability of sexual orientation to be 62% (Kendler, Thornton, Gilman, & Kessler, 2000). This means that 62% of why some people are gay and others are straight is due to genetic effects. The cartoon is right in saying this is higher than handedness, which has a heritability of around 25% (Medland, Duffy, Wright, Geffen, & Martin, 2006).

Older brothers.

One of the most established findings in all of developmental psychology is that each older brother increases the chance that a man will be gay. Younger brothers don't seem to have an effect and neither do sisters. In fact, siblings don't seem to be related to a women's sexual orientation at all. But among men, each older brother increases the chance of homosexuality by about 33% (Blanchard & Bogaert, 1996). It has been hypothesized that this effect is due to mothers producing antigens to male fetuses and that these antigens have effects on the developing brain (Blanchard, 2008). However, the cartoon seems to make it seem like this is a fact, when at this stage it is only a theory.

My therapist made me straight.

The video ends with a discussion of whether it is possible to change a person's sexual orientation through therapy or prayer. Conclusive research has yet to show this is possible and some very well respected doctors have said it is not possible (for a good summary of research in this area see Professor Gregory Herek's website). The video is correct in saying that all major mental health organizations have some out with statements saying that homosexuality is not a mental illness and attempts to change it are not advisable (for example, see the statement by the American Psychological Association).

I hope you enjoyed the cartoon. Share it by clicking the "Share/Email" button below and maybe if enough people watch it the statement "I don't believe in it, its unnatural, it's a choice," will become a think of the past.


Bagemihl, B. (1999). Biological exuberance : animal homosexuality and natural diversity (1st ed.). New York: St. Martin's Press.

Bell, A. P., Weinberg, M. S., & Hammersmith, S. K. (1981). Sexual Preference: Its development in men and women. Bloomington: Indiana University Press.

Blanchard, R. (2008). Review and theory of handedness, birth order, and homosexuality in men. Laterality, 13(1), 51-70.

Blanchard, R., & Bogaert, A. F. (1996). Homosexuality in men and number of older brothers. American Journal of Psychiatry, 153, 27-31.

Kendler, K. S., Thornton, L. M., Gilman, S. E., & Kessler, R. C. (2000). Sexual Orientation in a U.S. National Sample of Twin and Nontwin Sibling Pairs. The American Journal of Psychiatry, 157, 1843-1846.

Medland, S. E., Duffy, D. L., Wright, M. J., Geffen, G. M., & Martin, N. G. (2006). Handedness in twins: joint analysis of data from 35 samples. Twin Res Hum Genet, 9(1), 46-53.

Mustanski, B. S., Chivers, M. L., & Bailey, J. M. (2002). A critical review of recent biological research on human sexual orientation. Annual Review of Sex Research, 12, 89-140.

Sommer, V., & Vasey, P. L. (2006). Homosexual behaviour in animals : an evolutionary perspective. Cambridge ; New York: Cambridge University Press.

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