Another fraternal birth order research report

Title: Fraternal birth order and ratio of heterosexual/homosexual feelings in women and men.

Journal: Journal of Homosexuality. 2006; 51(4):161-74.

Authors: McConaghy N, Hadzi-Pavlovic D, Stevens C, Manicavasagar V, Buhrich N, & Vollmer-Conna U.


Studies of the 2-3% of persons who identify as homosexual found men but not women had more older brothers than persons who identify as heterosexual. The present study investigated the birth order in the approximately 20% of men and women who anonymously report some homosexual feelings, few of whom identify as homosexual. The number of older brothers and sisters was investigated in seven cohorts: 319 male twins; and 49, 54, and 61 female and 66, 116, and 50 male medical students. Both women and men who anonymously reported homosexual feelings had a greater mean number of older brothers and sisters than did those who reported no homosexual feelings. The difference was stronger in relation to brothers than sisters. The birth order effect was not related to the strength of the subjects’ degree of homosexual compared with heterosexual feelings. Its presence in women could not be accounted for by the widely accepted hypothesis that the birth order effect is due to amaternal immune reaction provoked only by male fetuses. The lack of relationship between the strength of the effect and degree of homosexual feelings in the men and women suggests the influence of birth order on homosexual feelings was not due to a biological, but a social process in the subjects studied. Investigating the neglected significant percentage of predominantly heterosexual men and women who anonymously report some homosexual feelings may aid in understanding the factors influencing sexual orientation, and identity. doi:10.1300/J082v51n04_09.

I haven’t seen the full report as yet, but will update when I do.

9 thoughts on “Another fraternal birth order research report”

  1. Dr Throckmorton,

    This is not a related study, but thought I woudl ask here. I think I asked about this elsewhere on your blog, but I will ask again becuase I don’t think you got to reply.

    Do you have any explanation for the Hershberger triplet study, that one of the triplets turned out gay, and showed gender non conforming behaviour from a very very young age, and the other 2 who didn’t turn out gay, did not?


  2. Timothy,

    You used that typo to try to catch up with me, didn’t you? 🙂

    You caught me on a day when I left my jump drive at home, so I can’t look the 1975 article up. The abstract is unclear to me, and my notes are ambiguous as well. Jeesh!

    Also, the 1981 abstract merely says “was no consistent trend for one therapy to be more effective than the other”. It looks like it will take some digging further into that art icle as well to understand exactly what responses they observed. “No more effective” doesn’t tell me much if he’s claiming success in covert sensitization as well.

    But I did recently look at the discussion in the 1981 article to learn McConaghy’s ethical thoughts on aversion therapy. Since he defended it as behavioral therapy rather than sexual reorientation therapy, that argument falls in line with what you said.

  3. Jim,

    It looks like he said that after aversion therapy gay men self reported less feelings and behavior but that the physical response as measured by penile volume. In other words, behavior and identity may have changed but (to paraphrase badly) the penis wants what the penis wants.

  4. I don’t know how he reaches that conclusion either, as he has not (apparently) ruled out other explanations unrelated to birth order. As the eldest of four boys (no sisters), I’m curious as to how he arrives at his conclusion.

    Nathaniel McConaghy is famous (some would say notorious) for having been very heavily involved with efforts to change sexual orientation in the 1960’s through the early ’70s. Some of his efforts involved electric shock and apomorphine injections (which induces extreme nausea). He finally concluded in a paper published in 1975 that none of those treatments were successful.

    And yet, he continued his research, publishing another paper in 1980 in which he presents the findings of 20 subjects who were treated by electric shock therapy. In the paper, he did acknowledge some of the ethical issues surrounding electric shock therapy. But he nevertheless defended it, not as a means of changing orientation, but for changing behavior — in his words, “behavior therapy”.

    Given his career in trying to forcefully change gay men’s behavior (and not women’s, that I know of), I have no doubt that his preference would lean toward social factors.

    This is the first paper I’ve seen in which he tries to examine factors influencing sexual orientation. And it’s likely to be the last. McConaghy passed away in 2005.

  5. My school does not get it either, although we used to. We are looking for it via loan. I think it takes an interesting twist by looking at the larger group of people who have experienced SSA at some time. I am not sure how they get to the conclusion that social factors are important but I of course, would expect that they are important.

  6. I’m very disappointed that the University of Arizona library decided to cancel its subscription to this journal. Although I find that much of what gets published is highly uneven (too much enthusiasm for queer theory nonsense for my tastes, and some studies appear to be published simply because they need to fill out an issue.), there are a lot of articles that garner quite a bit of attention.

    Maybe when I get to Dallas over Christmas I can drop in at a library there.

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