Some Concerns About Study Refuting Fraternal Birth Order Effect
December 1st, 2008
In January of 2008, Andrew Francis, an assistant economics professor at Emory University, released a paper in which he sought to apply analysis to the National Longitudinal Study of Adolescent Health (“Add Health”). His results are published in the October 2008 Journal of Sex Research and have gotten some attention from those who follow the nature / nurture debate.
His abstract includes the following:
For men, I find that having one older brother does not raise the likelihood of homosexuality. Although having multiple older brothers has a positive coefficient, it is not significant. Moreover, having any older sisters lowers the likelihood of homosexual or bisexual identity.
Unfortunately, I am neither a statistician nor am I able to fully comprehend his methodology or make heads or tails of his charts. I will leave that to those better skilled than I.
But I do have some observations that cause me to be reluctant to quickly accept Francis’ assertions.
Bias: I do have concern about Francis’ motivations. In August 2007 he released a paper in which he applied economic theory to sexual behavior and HIV and declared:
I present evidence that AIDS causes some men to shift from homosexual to heterosexual behavior, whereas AIDS causes some women to shift from heterosexual to homosexual behavior. Thus, sexual behavior may respond to incentives. I consider alternative hypotheses, including biological theories of sexual orientation and stigma-related survey bias, and argue that they are unlikely to explain the results.
In a paper written in March of this year, he proposed that a 1 to 2 year incarceration be the penalty for intentionally or unknowingly transmitting HIV. And while I find that paper to be troubling, he also released a paper in October that suggested that increased social tolerance towards homosexuality causes a statistical decrease in HIV infection rates.
So please note that I am not accusing Mr. Francis of bigotry; he’s not Paul Cameron.
But behind all of Mr. Francis’ work is the assumption that sexual behavior is malleable – at least on the edges – and it’s strongly implied that orientation (what Francis calls “desire”) is as well. So it should be greeted with caution that he has released a study that confirms what he has been presuming to be true for at least a year.
Contradictory: The most important question to ask of any study is, “Does this make sense”.
While it is entirely possible for ‘common knowledge’ to be completely wrong and for research to be a tool that overthrows myth and supposition, it doesn’t overthrow mathematics or logic. And Francis’ results reveal ‘findings’ that are hard to fathom.
Francis measures sexual behavior, sexual attraction, and two measures of sexual identity: not entirely heterosexual and not even close to heterosexual. But in Francis’ model these are often contradictory and in ways that are difficult to rationalize.
For example, being raised by a single dad has no material effect on sexual desire or sexual behavior but it is a positive indicator on identity. Say huh?
Yep. Boys raised by a single father are more likely to identify as gay but they aren’t attracted to the same sex or doing anything about it.
And a few other things he found… discoveries that will certainly delight some folks who have notions about classes and races.
Young black men are more attracted to guys and are having more sex, but (except for the nelly ones) they deny being anything but 100% straight. And if a boy is more educated, he’s more likely you are to declare himself gay (while remaining virginal), while blue-collar “straight” studs are out there humping like rabbits.
Frankly, that’s a worldview that is best left to porn.
Where it all falls apart for me is in the comparison of desire and identity.
I can get that there might be some demographic that expresses desire and romantic attraction to other men but cannot or will not identify as other than heterosexual. But it makes no sense whatsoever for a study to claim that there are four demographic subgroups that are more likely to identify as gay but aren’t attracted to the same sex.
Conclusion: You can measure the credibility of a research by whether their declarations of discovery are well supported by the data.
But consider this doozy:
Given the complexity of the empirical relationship between sexual orientation and the biodemographic and other correlates, it is likely that both biological and social mechanisms may play a role.
Wait. Social mechanisms? When, oh when, did the data address social mechanisms? The closest he gets is looking at college education.
But in Francis’ assumptions, if there’s no older brother effect then it’s likely that social mechanisms may play a role. Yikes.
I don’t know whether there is adequate evidence to conclusively prove whether there is a fraternal birth order effect in male sexual orientation. And I’ll let those who are more knowledgeable tell us if this model is conducted properly.
But I think I’ve seen enough to know that I’ll not place much reliance on this paper.