Talk:Fraternal birth order and male sexual orientation/Archive 1

Citations needed
Theres a lot of material being presented as hard facts in this stub. The references are listed but exactly what were they used for? Articles in Wikipedia are constantly updated and edited so everything needs to be directly cited.

Is Ray Blanchard's 1997 paper the earliest?

Could use some discussion of Histocompatibility-Y (H-Y) antigen hypothesis

No, there were papers in 1995 (also by Blanchard I believe) and 1996. I will locate the references and insert at least the earliest. Aftermath 00:33, 27 June 2006 (UTC)


 * I don't know if these properly identify older brothers in specific...


 * BLANCHARD, R. & SHERIDAN, P. M. (1992) Sibship size, sibling sex ratio, birth order, and parental age in homosexual and nonhomosexual gender dysphorics. J. Nerv. Ment. Dis. 180, 40­-47.


 * BLANCHARD, R. & ZUCKER, K. J. (1994) Reanalysis of Bell, Weinberg, and Hammersmith's data on birth order, sibling sex ratio, and parental age in homosexual men. Am. J. Psychiat. 151, 1375-­1376.

Pete.Hurd 05:59, 27 June 2006 (UTC)


 * Blanchard has also suggested (see https://twitter.com/blanchardphd/status/953779971008458752) that references to these three studies should be added:
 * https://link.springer.com/article/10.1007%2Fs10508-017-1007-4
 * https://link.springer.com/article/10.1007%2Fs10508-017-1134-y
 * http://www.pnas.org/content/115/2/302
 * Jeremy Malcolm (talk) 00:12, 18 January 2018 (UTC)

homosexuality a pathology?
There is an underlying problem with this article in that it is premised on the assumption that homosexuality is a disorder of some kind. While 'fraternal birth order theory' may seek explanations for homosexuality or predictions of homosexuality - this theory is based on the premise that homosexuality is a disorder (consider the opposite notion of a theory that would seek to predict or explain heterosexuality). This wikipedia entry inadvertently (?) sides with this assumption. This was reflected first in the term 'observation' being used in the initial sentence rather than the more neutral and detached term 'theory' - i subsequently replaced it. There, however, remains several other sentences that are less easy to tweak into shape. such as: "The fraternal birth order effect is the strongest known predictor of sexual orientation..." It is the 'fraternal birth order effect theory' that seeks to predict sexual orientation - general society (and the medical establishment) no longer seeks this as there is no longer the assumption of homosexuality as abnormal. The problems in this article are a consequence of the premise of homosexuality as abnormality. Can anyone assist in tweaking the language so it more accurately reflects the neutrality of encyclopedic entries? p.s. this is my first discussion contribution - thanks for giving me material to inspire me enough! Piginmud 07:30, 31 January 2007 (UTC)

no engagement with my point?
Hi, I am curious as to why my alteration from 'observation' to 'theory' was re-changed without any discussion, or perhaps even refutation, of the issues i raised... isn't that the point of the discussion page/wikipedia? Piginmud 05:31, 1 February 2007 (UTC)


 * In the sentence "In psychology the "fraternal birth order" effect is the name given to the observation that the more older brothers a man has, the greater the probability is that he will have a homosexual sexual orientation." Observation is the proper descriptor. A theory would require a theoretical framework to explain the why the observation exists.  Note that the HY-antigen hypothesis, is just that a hypothesis, rather than a theory or observation. Pete.Hurd 15:27, 1 February 2007 (UTC)


 * No, it is a theory the way it is phrased as generally applicable to the entirety of humanity. If it stated that it has been observed that some or X amount of correlation was made, that would be an observation. It is presented as a hard fact when it is clear the sources do not support it being so. This is a theory which is limited to the regions and variables included. Mark
 * Observation is still the proper description of FBO effect as a phenomenon; theory means to explain the why, as Pete says. Mark, your concern appears to be that the observation is limited to some studies, so I will qualify the statement as such. --Pekoebrew (talk) 23:56, 17 December 2012 (UTC)

Title
I think that the title "Fraternal birth order" is ambiguous, in that it could be understood as refering to the general relationship between brothers, and not specifically to the effect that the number of older brothers a man has is suggested to have on his sexual orientation. Similarily, I think that the title "Fraternal birth order effect" would be ambiguous, as birth order has long been proposed to have an influence on what a person is like, so the title "Fraternal birth order effect" would not reveal that the specific effect of birth order which this article discusses is upon a man's sexual orientation. Thus, I will retitle this article "Fraternal birth order and sexual orientation," which will reflect its scope better, as well as maintain consistency with the titling of a related article, Handedness and sexual orientation. -Severa (!!!) 00:20, 7 June 2007 (UTC)

Maternal Immune Hypothesis assumes Homosexuality as Abberation
This is somewhat related to the thread above. The Blanchard "studies" propose an immune reaction by the mother against the fetus, but there is absolutely no evidence to suggest this. If you read the original article, which by the way is in the Journal of THEORETICAL Biology, it gives no data support to this hypothesis. What little evidence they do present about the H-Y protein complex was done in mice. It can't possibly be extrapolated to human sexuality. I have a real problem with this "theory" because it suggests homosexuality comes about because the mother's body is trying to attack the fetus, in essence an abberation of what the "ideal" should be (heterosexual)... if there were any empirical evidence to support this I would take more heed, but I feel like this "researcher" is trying to spread his own agenda with no basis whatsoever. At least it doesn't say the fetus is "feminized", which I corrected on another page. The last sentence in this article is confusing - I'm not sure if the effect holds true for right-handed or non-right-handed men.Gimmethoseshoes (talk) 21:23, 15 March 2008 (UTC)

Okay, so as there's been no discussion, and as Pigmund has also found the same fault with this article and its non-science, I'm reducing the paragraph about maternal immune hypothesis to only mention it as that.Gimmethoseshoes (talk) 06:34, 19 June 2008 (UTC)


 * OK, so let me see if I understand this. You deleted the sentence "It is hypothesized that the fraternal birth order effect may be caused by increasing levels of antibodies produced by the mother to the histocompatibility Y-antigen with each son." because the hypothesis was proposed in a paper published in a scientific journal whose title contains the word "theoretical" and may be construed to provide support for a point of view with which you disagree? Pete.Hurd (talk) 18:59, 19 June 2008 (UTC)

I agree with Pete.Hurd. Hy-antigen is a theory to explain an observation, and it's described only as a theory. Gimmethoseshoes can disagree with the theory, of course, but the purpose of an encyclopedia is to present as much information as is necessary for readers to come to their own decision, not to come to the editors' opinion. I think the fuller description should remain. —MarionTheLibrarian (talk) 19:14, 19 June 2008 (UTC)

McConaghy (2006)
In 2006, the Journal of Homosexuality printed an article entitled Fraternal birth order and ratio of heterosexual/homosexual feelings in women and men. In the article, McConaghy ran some experiments, the result of which he said "suggests the influence of birth order on homosexual feelings was not due to a biological, but a social process in the subjects studied." After I inserted the results from this study into the article, it was reversed saying "Anyone can fail to find evidence by just using bad methods." The Journal of Homosexuality decided that his paper was good enough to print. I have not seen any evidence that his methods were flawed. Can you please be more specific as to why you believe McConaghy's methods were flawed enough were they don't even deserve mention in this article? Joshuajohanson (talk) 00:13, 12 July 2008 (UTC)

The Journal of Homosexuality is an extremely poor source; it has about the lowest impact factor of any sex/gender journal in print. McConaghy's "suggestion" of a social effect has been ruled out by the Bogaert (2006) paper (which was published in one of the highest impact journals in print). Remarkable claims require remarkable sourcing, and McConaghy's claim in JOH does not provide that. —MarionTheLibrarian (talk) 10:53, 12 July 2008 (UTC)


 * How would it be possible to cover mistaken theories (surely a worthwhile enterprise) if 'suggestions' that others have ruled out were not mentioned? Skoojal (talk) 22:55, 12 July 2008 (UTC)


 * I would have no objection to covering McConaghy's idea the way you indicate (as a mistaken theory). This might be something along the lines of 'A social explanation of the fraternal birth order effect was suggested by McConaghy (ref), but subsequent data by Bogaert on adopted brothers could not be accounted for a social explanation (ref Bogaert).' The original text, however, posited a social theory as an alternative (equally valid) explanation, which is not correct.
 * — James Cantor (talk) (formerly, MarionTheLibrarian) 19:45, 15 July 2008 (UTC)


 * I think this is the most sensible thing to do, include McConaghy's hypothesis & data, and then discuss subsequent data which runs contrary to the idea. IRL, I'd be looking for a power analysis of McConaghy's data, it's a non-significant result, but where is the upper limit of the 95%CI on the effect size?  We know it spans zero, but does it also include the effect sizes found by studies that have found significant effects?  (Note: I havn't yet read McConaghy's paper, perhaps this is aready addressed). Pete.Hurd (talk) 20:28, 15 July 2008 (UTC)


 * The Journal of Homosexuality is a perfectly acceptable source. Besides, Bogaert's paper didn't rule out anything.  He simply said his results "strongly suggest a prenatal origin to the fraternal birth-order effect."  It did not say it rules out any other possibilities.  This whole topic is very new, so I don't think anything is a particularly remarkable claim at this point.  Again, I see no evidence that McConaghy's methods were flawed.  It is important to show both Bogaert's "suggestion" as well as McConaghy's "suggestion" until some consensus is reached.  I see no evidence of a consensus in the medical field. Joshuajohanson (talk) 22:19, 14 July 2008 (UTC)


 * That journal qualifies as a reliable source (by WP standards) with regards to making a claim on their own; however, when that claim contests one made by a large number of superior sources, it cannot be treated as equal. One-off claims made in poor sources are fringe, and need to treated as such, not as equally valid alternatives (as the original edit did).  No claim in science will ever be unanimous, but is an error to treat them all as equal.  They need to be treated in proportion to their RS's, and the supporters for social explanations of the older brother effect are few and far between.
 * — James Cantor (talk) (formerly, MarionTheLibrarian) 19:52, 15 July 2008 (UTC)


 * I wouldn't go so far as to call it fringe. Why does one result suggesting a biological component have to contest with one that suggests a social process?  Personally, I don't see why it can't be a combination of the two.  Sexuality is very complex, and I think any attempt to narrow it down to just one cause is flawed, but then that is my opinion.  I am perfectly fine with not treating it as equal with the other theories.  Go ahead and reword it so it doesn't have as much weight as the other theories.  Just don't erase it all together.  My biggest beef is treating it as if the results are conclusive and the answer is clear.  The question is far from answered and the article should reflect that. Joshuajohanson (talk) 22:35, 15 July 2008 (UTC)
 * "Why does one result suggesting a biological component have to contest with one that suggests a social process?" well, the question is whether the FBO effect is a function of the number of boys that gestated in the mothers womb before the focal boy, or whether the FBO effect is a function of the number of older boys the focal boy is raised with (or the third option, as you suggest a bit of both). My understanding is that the evidence is pretty overwhelmingly for the former, and not the latter or the both option. "Sexuality is very complex" aye, agreed, but if we narrow our focus to just the FBO (which we know accounts for, at most, a small minority of the variation in sexual orientation in men) then what do we know about that one little slice?  Womb effect or raising effect, or both?  That's an intentionally simplified, reductionistic, much-ignoring, but fairly straight-forward, empirical question. Pete.Hurd (talk) 22:53, 15 July 2008 (UTC)
 * In response to James Cantors above assertion that the claims of social explanation of the effect cannot be treated as equal to the ones made by "a large number of Superior sources". I see 4 studies mentioned in this article.  One disputes the entire idea, two support it and a genetic or hormonal pre-birth concept, and one a social explanation.  How is this a large number of superior sources? 206.126.163.20 (talk) 17:42, 27 October 2008 (UTC)
 * Oh, come on, Conaghy's suggestion just does not hold water logically. --77.236.203.210 (talk) 06:40, 23 May 2015 (UTC)

Only four are mentioned in the WP article, but (of course) the actual published literature is much larger. (A WP article need only contain a summary, not an exhausive list of the entire literature.) The following are the articles that I have on hand. One should note that the following list includes some of the highest impact scientific journals in print. — James Cantor (talk) 17:50, 27 October 2008 (UTC)
 * Blanchard, R. (1997). Birth order and sibling sex ratio in homosexual versus heterosexual males and females. Annual Review of Sex Research, 8, 27–67.
 * Blanchard, R. (2001). Fraternal birth order and the maternal immune hypothesis of male homosexuality. Hormones and Behavior, 40, 105–114.
 * Blanchard, R. (2004). Quantitative and theoretical analyses of the relation between older brothers and homosexuality in men. Journal of Theoretical Biology, 230, 173–187.
 * Blanchard, R. (2008). Review and theory of handedness, birth order, and homosexuality in men. Laterality, 13, 51–70.
 * Blanchard, R., Barbaree, H. E., Bogaert, A. F., Dickey, R., Klassen, P., Kuban, M. E., & Zucker, K. J. (2000). Fraternal birth order and sexual orientation in pedophiles. Archives of Sexual Behavior, 29, 463–478.
 * Blanchard, R., & Bogaert, A. F. (1996). Biodemographic comparisons of homosexual and heterosexual men in the Kinsey interview data. Archives of Sexual Behavior, 25, 551–579.
 * Blanchard, R., & Bogaert, A. F. (1996). Homosexuality in men and number of older brothers. American Journal of Psychiatry, 153, 27–31.
 * Blanchard, R., & Bogaert, A. F. (1997). Additive effects of older brothers and homosexual brothers in the prediction of marriage and cohabitation. Behavior Genetics, 27, 45–54.
 * Blanchard, R., & Ellis, L. (2001). Birth weight, sexual orientation, and the sex of preceding siblings. Journal of Biosocial Science, 33, 451–467.
 * Blanchard, R., & Klassen, P. (1997). H-Y antigen and homosexuality in men. Journal of Theoretical Biology, 185, 373–378.
 * Blanchard, R., & Lippa, R. A. (in press). Birth order, sibling sex ration, handedness, and sexual orientation of male and female participants in a BBC internet research project. Archives of Sexual Behavior.
 * Blanchard, R., & Sheridan, P. M. (1992). Sibship size, sibling sex ratio, birth order, and parental age in homosexual and nonhomosexual gender dysphorics. Journal of Nervous and Mental Diseases, 180, 40–47.
 * Blanchard, R., & Zucker, K. J. (1994). Reanalysis of Bell, Weinberg, and Hammersmith’s data on birth order, sibling sex ratio, and parental age in homosexual men. American Journal of Psychiatry, 151, 1375–1376.
 * Blanchard, R., Zucker, K. J., Bradley, S. J., & Hume, C. S. (1995). Birth order and sibling sex ratio in homosexual males adolescents and probably prehomosexual feminine boys. Developmental Psychology, 31, 22–50.
 * Blanchard, R., Zucker, K. J., Siegelman, M., Dickey, R., & Klassen, P. (1998). The relation of birth order to sexual orientation in men and women. Journal of Biosocial Science, 30, 511–519.
 * Bogaert, A. F. (2003). The interaction of fraternal birth order and body size in male sexual orientation. Behavioral Neuroscience, 117, 381–384.
 * Bogaert, A. F. (2003). Number of older brothers and sexual orientation: New tests and the attraction/behavior distinction in two national probability samples. Journal of Personality and Social Psychology, 84, 644–652.
 * Bogaert. A. F. (2004). The prevalence of male homosexuality: The effect of fraternal birth order and variations in family size. Journal of Theoretical Biology, 230, 33–37.
 * Bogaert, A. F. (2007). Extreme right-handedness, older brothers, and sexual orientation in men. Neuropsychology, 21, 141–148.
 * Bogaert, A. F., & Cairney, J. (2004). The interaction of birth order and parental age on sexual orientation: An examination in two samples. Journal of Biosocial Science, 36, 19–37.
 * Bogaert, A. F. (2006). Biological versus nonbiological older brothers and men’s sexual orientation. Proceedings of the National Academy of Sciences of the United States of America, 103, 10771-10774.
 * Cantor, J. M., Blanchard, R., Paterson, A. D., & Bogaert, A. F. (2002). How many gay men owe their sexual orientation to fraternal birth order? Archives of Sexual Behavior, 31, 63–71.
 * Ellis, L., & Blanchard, R. (2001). Birth order, sibling sex ratio, and maternal miscarriages in homosexual and heterosexual men and women. Personality and Individual Differences, 30, 543–552.
 * Green, R. (2000). Birth order and ratio of brother to sisters in transsexuals. Psychological Medicine, 30, 789–795.
 * Poasa, K. H., Blanchard, R., Zucker, K. J. (2004). Birth order in transgendered males from Polynesia: A quantitative study of Samoan fa'afafine. Journal of Sex and Marital Therapy, 30, 13–23.
 * Puts, D. A., Jordan, C. L., & Breedlove, S. M. (2006). O brother, where art thou? The fraternal birth-order effect on male sexual orientation. Proceedings of the National Academy of Sciences, 103, 10531–10532.
 * Slater, E. (1962). Birth order and maternal age of homosexuals. Lancet, 1, 69–71.
 * Zucker, K. J., Blanchard, R., & Siegelman, M. (2003). Birth order among homosexual men. Psychological Reports, 92, 117–118.

I Removed the current 1-sentence McConaghy study reference, as this 12-year old study is now contradicted by an increasingly large body of well-performed, statistically valid studies. I am not aware of any independent support for the McConaghy study. JDowning (talk) 20:53, 29 January 2019 (UTC)
 * Pinging James Cantor so that he is aware of this removal in case this article is no longer on his watchlist or he is busy enough that he might miss it. As for whether or not McConaghy should be mentioned in the article, it depends on WP:Due weight. A theory that has been contradicted can be included if that theory has been significantly reported on in the literature. Wikipedia commonly notes that previous theories, including minority ones and WP:Fringe ones, have been contradicted or shown to be incorrect by later research. Flyer22 Reborn (talk) 01:51, 30 January 2019 (UTC)


 * I would also ping Joshuajohanson, Skoojal and Pete.Hurd, but Joshuajohanson and Pete.Hurd are retired and Skoojal was identified as a WP:Sock. Pinging JDowning. JDowning, like I stated, Wikipedia commonly notes that previous theories, including minority ones and WP:Fringe ones, have been contradicted or shown to be incorrect by later research. Not sure if you read the above discussion. If you did not, consider doing so. Flyer22 Reborn (talk) 01:59, 30 January 2019 (UTC)


 * I did read the discussion above, noting the last comment about McConaghy was 10 years ago (Oct 27 2008), and noting the reproducibility of the study was questioned at the time. The article has increased in size ten-fold since that point, and 54 more references have been added, none of them supporting the McConaghy study.  As you stated, unusual/isolated theories "can be included if that theory has been significantly reported on in the literature"--but the McConaghy study has stood, alone and unsupported, in this wiki article for a decade---while every other section has accumulated many other supporting citations.  If the McConaghy study's theories have been significantly reported on in the literature, I agree it should be re-added, but with those supporting citations.JDowning (talk) 04:07, 30 January 2019 (UTC)

"After repeating the experiment done by Blanchard"
Bearman's study covers twins, which is something I can neither confirm nor deny happened in Blanchard's studies. The word "repeating" bothers me because I am inclined to believe Blanchard and disbelieve Bearman. Can someone who has access to the actual sources cited confirm or deny that the experiment performed by Bearman actually "repeats" what Blanchard studied? If not, within a few weeks I will remove the offending phrase. EAE (Holla!) 07:53, 12 February 2009 (UTC)

"recent" research
This line is being modified, I see absolutely no reason to keep it, not only are Blanchard's experiments over 15 years old, this effect was actually originally noticed in the 60s by Slater. Slater, E. (1962). Birth order and maternal age of homosexuals. Lancet, i. pp. 69–71. Valethar (talk) 10:43, 23 March 2010 (UTC)

Alternative to the maternal immunity hypothesis
The hypothesis that as a mother has more male children, her body becomes increasingly efficient at suppressing the maleness of subsequent male children in utero is not a surprising hypothesis from a researcher who believes exclusively androphilic male-to-female transsexualism is "an extreme form of homosexuality". But at least one survey suggests the opposite occurs: We found that the male 2D:4D ratio, which is unlikely to be influenced by social factors, also varies with the number of older brothers. The ratio was significantly more masculine in men with two or more older brothers than in men with no older brothers ... Finger measures indicate that men with more elder brothers, including those men who develop a homosexual orientation, might be exposed to greater than normal levels of prenatal androgen." Nature Each male child seems to make a mother more conducive--not less--to maleness. It may be that hypermasculine males are more inclined to homosexuality. Maybe they have mild autism (Asperger's), which is also a result of hypermasculinization and which I suspect (and as do others, but it's poorly researched) is correlated with homosexuality. (Autistics are less aware of taboos, and male autistics--the great majority of autistics are male--may struggle to relate to the opposite sex sexually.)

The maternal-immunity hypothesis isn't described in the article. A reference to the apparent hypermasculinity of males with older brothers would nicely accompany a description.

And if you'll allow me a little digression... Rather than David France's speculation in a 2007 New York Magazine article that "homosexuals may be simultaneously more feminine and more masculine", researchers are likely conflating two distinct types of homosexual males, namely masculine and feminine types. The feminine male has an androphilic sexual preference for the reason women do; the masculine male has it for the any number of reasons other masculine males have non-mainstream sexual preferences. Does it surprise anyone that males with feminine speech, dress, and interests also have feminine cognitive skills, digit ratios and hypothalamuses ? All the research has found is that feminine males are feminine and likely born that way. Failing to distinguish the two groups allows the feminine homosexual male to represent all homosexual males, particularly when researchers find samples in gay spheres which have less masculine males than the entire homosexual population. (Consider: if you're accepted as a mainstream male, why would you segregate yourself?) The research discourages (open) homosexuality and bisexuality in masculine males by firmly associating it with femininity, thereby regulating behavior more efficiently than any religious, legal or moral code. 75.132.162.206 (talk) 13:32, 17 November 2010 (UTC)


 * Assuming the maternal X-linkage is being conflated, there is one theory not mentioned which is significant enough to bear on this topic. Older fathers have genes that require more DNA repair which means more deletions and mutations express.  Homosexuality may be the sexual evolutionary approach for dealing with these issues since sexual evolution developed out of a need for each successive generation to have greater fitness and this evolution has two-fold utility.  First, the offspring's genes use the strategy to not reproduce or compete with others that may promote more ideal or stable future reproduction.  The mutations may not be useful ones or be ones directly related to hampering future fertility in men.  Second, their role is supportive as the gay-uncle theory would suggest.71.191.160.148 (talk) 07:10, 14 April 2011 (UTC)


 * As for Aspergers, I've read similar and think this should be included as well. Now to find citations.71.191.160.148 (talk) 07:10, 14 April 2011 (UTC)

Same mother
My understanding is that this effect only happens with having multiple older brothers from the same mother; not just having older brothers. (So full biological older brothers and older half brothers that share the same mother would fall under the effect, while older adopted brothers or older half brothers that share the same father will not fall under the effect). This seems an important stipulation to the hypothesis that is barely mentioned in the article. 71.190.228.146 (talk) 05:59, 7 May 2015 (UTC)

Bearman & Bruckner's study
This study sought to test the strength of the relationship between fraternal birth order effect and 'same-sex attraction' (which may be occasional, fleeting or even once in a lifetime) in adolescents to make judgments about homosexuality even though fraternal birth order effect is strongly related to homosexuality (an enduring same-sex attraction, not an occasional, fleeting or once in a lifetime one). I don't see how this study can be used to make claims about the relationship between fraternal birth order effect (FBOE) and homosexuality.

The flaw in this study that casts greatest doubt on its validity is how it defined the term 'homosexual'. It defines 'homosexual' as someone who has ever had an attraction to members of the same sex even though homosexuality is an enduring pattern of attraction to members of the same sex. So this study has not removed the possibility of the presence of bisexuals and heterosexuals (who experienced attraction to members of the same sex at some points in their lives, under certain circumstances) in the sample. This is significant as the etiology of homosexuality is different from that of bisexuality or heterosexuality, especially when it comes to the fraternal birth order effect, i.e. the effect has not been observed to influence bisexual or heterosexual orientations.

Further, the only adolescents in the sample of this study that one can accept as homosexual (i.e. people who possess an enduring same-sex attraction) with some confidence are adolescents who engaged in same sex relationships. However this study states that "The number of adolescents involved in same sex relationships or same sex sexual behavior is too small for serious analysis consequently,we focus on same-sex romantic attraction" and that "the number of adolescents involved in homosexual relationships is too small in our sample to assess genetic influence statistically with any confidence." In other words, this study has not studied the only group that could have been reasonably assumed to be actually homosexual.

Further, the tabulated results do not mention how many of the adolescents surveyed had older siblings, specifically older brothers. The authors merely give us the supposed percentages of adolescents with older siblings in the text of the study without mentioning how they came to this conclusion, whether these siblings were step-siblings or biologically related, how many were born of the same mother and how many by surrogates, exactly how many older brothers the adolescent twins had, if any older brothers were stillborn or had died, etc. (all important points when it comes to the FBOE). Telling us the exact numbers of (presumably) homosexual adolescents with older brothers was important as the entire conclusion of this study (that FBOE supposedly does not influence the formation of a homosexual orientation) rests on their statement that the number of (presumably) homosexual adolescents with older brothers is less than the number of (presumably) homosexual adolescents without older brothers (a finding that, if correct, seems to be contrary to what the FBOE states).

Further, the FBOE has been determined to be a cause of homosexuality only in right-handed homosexuals. This study however did not ask people about their handedness, nor did it check for the FBOE in right-handed adolescents. Also, the current Wiki article and Bearman & Bruckner's study claim that studies showing a fraternal birth order effect used indirect reports on siblings' sexual orientation, but Bearman & Bruckner have admitted in their study that "Kendler et al, 2000" was indeed free from this flaw and still reported a fraternal birth order effect.

Finally, the study claims that: "This study shows that for OS [opposite sex] twins, in the absence of strong gender socialization, the proportion of male adolescents with same-sex attraction is twice as high as observed in the population as a whole." However, the study did not at all determine or try to determine whether strong gender socialization was indeed absent from the upbringing of the OS twins or not; the authors are merely assuming that it was.

In light of all this, Bearman & Bruckner's study seems very unreliable. I feel we should remove the text that uses their study as the sole citation. — Preceding unsigned comment added by Human10.0 (talk • contribs) 16:24, 11 November 2015 (UTC)


 * Human10.0, even though the term homosexuality is commonly used to mean any same-sex sexual attraction or same-sex sexual activity, I understand what you mean. You are referring to homosexuality in the sexual orientation sense. Furthermore, the term homosexual, when used to describe a person, is usually understood to mean the sexual orientation aspect. If it's the behavior that is homosexual, scholars will usually clarify that with "homosexual behavior" and similar. But I don't see that we should exclude the Bearman & Bruckner's study in its entirety. We should include it with WP:Due weight, and add quality opposing literature on the topic to go with it. There is scholarly commentary on the study. Flyer22 Reborn (talk) 21:03, 12 November 2015 (UTC)


 * Thanks for replying Flyer22 Reborn. I will try my best to find relevant scholarly commentary but may I ask why you want to keep the study in the Wiki article, considering that it does not define 'homosexual' in the sexual orientation sense and most of the sample probably did not have a homosexual orientation whereas this Wiki article is specifically about male sexual orientation? To me, using this study as a citation would only seem appropriate in a Wiki article about the FBOE and 'same-sex attraction', not sexual orientation. −Human10.0 (talk) 22:23, 12 November 2015 (UTC)


 * I think it should be included because, from what I can see, Bearman and Bruckner were considering the study in the sexual orientation sense. "[S]omeone who has ever had an attraction to members of the same sex" covers gay/lesbian (homosexual) people in addition to heterosexual and bisexual people. As you noted, Bearman and Bruckner were clear about why they focused on same-sex attraction as opposed to "the number of adolescents involved in homosexual relationships." It's not like they were trying to exclude gay/lesbian people. Furthermore, romantic/sexual attraction is a stronger indicator of sexual orientation than sexual behavior is. And reliable sources count the Bearman and Bruckner study as part of the research on fraternal birth order and male sexual orientation. Therefore, not mentioning the study at all in this article would be excluding an aspect of the literature that has been considered by academics and it would be a disservice to our readers.


 * On a side note: Since this article/talk page is on my WP:Watchlist, there is no need to be WP:Ping me to it. Flyer22 Reborn (talk) 08:57, 13 November 2015 (UTC)


 * I also think the limitations of the study, which you noted above, should be mentioned in the article. Flyer22 Reborn (talk) 09:04, 13 November 2015 (UTC)


 * Thanks for sharing your thoughts. I feel that even if the authors considered this study in a sexual orientation sense, it is evident that this study does not explore the relationship between the fraternal birth order effect and sexual orientation. And even though they did not purposely exclude homosexuals, they did define 'homosexual' in a way that ensured over-representation of non-homosexuals in their sample, which may have been the reason why the FBOE was not detected in their study, considering that it only applies in the case of male homosexuals. The fact that their definition of 'homosexual' covers people of all orientations, as you noted, is pertinent as this is a Wiki article on an effect related specifically to homosexual orientation.


 * Regarding indicators of sexual orientation, I would like to quote one of Bruckner's other studies that states: "Researchers commonly recognize attraction, behavior, and identity as 3 components of sexual orientation and have noted the importance of examining all 3 of them." While sexual attraction is indeed a good indicator of sexual orientation, it has been observed that the number of people who have experienced at least some same-sex attraction (at some instance(s) or throughout life) outnumbers people who identify as LGB. While, it is probable that many people who have expereinced same-sex attraction but don't identify as LGB are indeed LGB, it is unlikely that there are no heterosexuals in this group. Similarly I feel it is unlikely that Bearman & Bruckner's sample did not contain a significant number of heterosexuals.


 * That being said, you make a sound point about the inclusion of Bearman & Bruckner's study in light of its presence in the literature on the FBOE and I agree that the limitations of this study should be included as well. But a problem is that there are not enough sources that critically appraise this study (probably because it's not that well-known; so far I have only been able to locate one appraisal) hence there aren't enough secondary sources that highlight all of its glaring methodological flaws. So is there a way the limitations I noted can still be added to the article? You mentioned that there is scholarly commentary on this study, I would really appreciate it if you could share it. −Human10.0 (talk) 23:42, 13 November 2015 (UTC)


 * When it comes to limitations of the study, I was mainly referring to what Bearman and Bruckner stated about the study, such as "The number of adolescents involved in same sex relationships or same sex sexual behavior is too small for serious analysis [...]." Including how they defined homosexual or homosexuality would also be fine. As for my statement that "There is scholarly commentary on the study.", I was referring to academic commentary I'd read years back when researching the matter in my local libraries and when I was out of state. I also remember reading criticism of the study. But looking on Google Books, I don't see any substantial commentary on the topic, from good sources or otherwise. That will likely change in the future. And here is a link to articles/studies citing the aforementioned Bearman and Bruckner research on Google Scholar. Flyer22 Reborn (talk) 07:29, 14 November 2015 (UTC)


 * Okay, I will add the limitations mentioned by the authors and their definitions of terms. I did look up some books on Google Books before but I will thoroughly search for commentary in the resources you have linked to. Unfortunately there are not a lot of public libraries where I live and I doubt they would have material on sexual orientation, otherwise I would have consulted them too. Thank you for your help Flyer22 Reborn. Your input is greatly appreciated. –Human10.0 (talk) 19:41, 15 November 2015 (UTC)

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Recent big expansion
Human10.0, I'm not sure that this recent big expansion should have been carried out. That's a lot of WP:Primary sourcing, and summarizing is better in the case of some aspects. Also keep WP:Editorializing in mind. None of your content is WP:Synthesis, is it? Flyer22 Reborn (talk) 19:03, 26 August 2017 (UTC)
 * Thanks for sharing your concerns about the expansion Flyer22 Reborn. I was forced to make a large edit because I felt that if I added the info to the article in multiple stages, the article would have become a difficult (and repetitive) read before assuming a proper readable form when all the current info had been added. I also wasn't sure whether I'd be able to incrementally add the info on a regular basis, so I decided to make a large edit rather than making small ones that would have resulted in a half-done article requiring further edits to paint a coherent & complete picture.


 * Regarding primary sourcing, I have tried to avoid citing only the primary source. For example, after adding a statement to the Wiki article, I have cited the primary study that made the statement and then cited any secondary studies that made the same statement. I have frequently used the 2017 meta-analysis, the 2011 review, the 2004 meta-analysis, and other secondary sources for this purpose. Also, I've given a single citation after some statements but that citation isn't the primary source, it's secondary, e.g., the study cited after stating that the FBOE has been demonstrated in both patients & non-patient volunteers is a study that just mentioned that the FBOE has been found in both patients & non-patient volunteers (based on evidence from previous studies); searching for the FBOE in patient & non-patient volunteers wasn't that study's focus. However, there are some places in the article where secondary sources can be added and I shall do that.


 * Regarding WP:EDITORIALIZING, I will re-read the article and remove any wording that seems like editorializing. I'm personally fine with the removal of the word "important" from the sentence "Research over the years has established several important facts" in the Overview section. To clarify, the cited study had described the facts as "important" so I stated it as such, I did not add the word "important" in the sentence based on my own judgment.


 * Regarding WP:SYNTH, the content I added isn't synthesis. I have tried to stay as close to the source texts as possible. For example, I stated that due to the FBOE, a male with one older brother has a 2.6% chance of being homosexual while a male with four older brothers has a 6.0% chance. Mathematically, one can calculate what the chances of being homosexual are if a male has five, six, seven older brothers but I did not state those chances to the Wiki article because the cited study only mentions what the chances are up till four older brothers. I have made one error though: I've mistakenly referred to a review as a meta-analysis in the article. I will correct that. —Human10.0 (talk) 08:31, 3 September 2017 (UTC)


 * Thanks for explaining. And I wasn't stating that all of your content was WP:Synthesis; I was simply asking if any of it was. As for WP:Editorializing, I've seen you add some content that I would consider WP:Editorializing. If the source is using the word(s), that's a different story, but we still shouldn't be stating "It is important to note," and similar. Doing so is pretty much talking to the reader; see WP:YOU for what I mean about talking to the reader. Flyer22 Reborn (talk) 20:01, 3 September 2017 (UTC)
 * Okay, thank you for your feedback and for directing me to WP:YOU. Do you have a particular part of the article in mind that you feel should be edited so it does not seem editorialized or at odds with WP:YOU? If so, kindly let me know. —Human10.0 (talk) 13:25, 4 September 2017 (UTC)

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Potentially misguiding wording & Danish study
Rafe87, the fraternal birth order effect is not a theory, it is an observed effect. Adding the words "according to supporters of the theory" and the like to sentences in the article casts unfounded doubt on the existence of the FBOE, gives the impression that a well-recognized, valid, equally large opposition to the existence of the FBOE is present in the scientific community (which is not true), gives the impression that studies demonstrating the FBOE have been affected by experimenter bias (which is not true) and is your personal interpretation of the primary source (which is not allowed as per WP:PRIMARY). The existence of the FBOE is well-established in sexual orientation research. And as the article states, the finding of the FBOE by Blanchard as well as by independent researchers shows that the studies demonstrating the effect aren't effected by experimenter bias.

There is no need to replace the statement "the naturally occurring odds of a male child (with no older brothers) being homosexual are estimated to be 2%" with "According to defenders of the theory, the naturally occurring odds of a male child (with no older brothers) being homosexual are estimated to be 2%." The 2% odds of homosexuality specifically for males with no older brothers are supported by empirical research.

Regarding the Danish study, Frisch and Hviid (2006): It was a study of correlates of opposite-sex and same-sex marriage in a specific sample of Danish men and women. But same-sex marriage was not a reliable proxy for homosexuality (i.e., the findings related to same-sex marriage cannot be interpreted as if they are findings about homosexual orientation) and the Danish study has multiple other problems. For example, Frisch and Hviid (2006) studied same-sex marriages occurring after 1989 but studied opposite-sex marriages occurring after 1970. This can introduce artifactual differences between the same-sex and opposite-sex married groups that can affect detection of a fraternal birth order effect. There were also apparent problems in the methods used in identifying and counting sibs from official records, which Frisch and Hviid acknowledged and corrected in a later partial re-analysis. Additionally their statistical procedures were unlike those used in any other study on the FBOE. There are more recognized problems that may be listed but I think these should suffice to demonstrate that Frisch and Hviid (2006) had a number of limitations that can prevent demonstration of the FBOE. Re-analysis of Frisch and Hviid's (2006) data (to produce results comparable in form to other studies of the FBOE) did, in fact, show that same-sex married men had significantly more older brothers and older sisters, with significantly fewer younger brothers and younger sisters as well. –Human10.0 (talk) 19:23, 7 September 2017 (UTC)
 * This is ridiculously dogmatic. Plenty of researchers do not accept it as the final say but see it as one competing theory among many. Wikipedia talk pages are not the place to argue which theories are the correct ones. We merely try to reflect the scientific discourse, without taking the party of any of the voices participating in this discourse. The Danish study was released in a reputable journal showing data that disagreed with the FBO effect. I'm aware that Blanchard and others objected to the data, but Frisch has responded and other researchers, such as Kishida and Rahman (2015) think, Blanchard's objections were unfounded. Please, do not change my edits, there's nothing controversial in presenting the FBO theory as it is, a theory. Rafe87 (talk) 23:32, 7 September 2017 (UTC)
 * I should also tell you that if you're one of the researchers who've published papers on the theory, you're advocating of it, and criticism of deviating research, may constitute a personal interest.Rafe87 (talk) 23:34, 7 September 2017 (UTC)


 * We will not be "try[ing] to reflect the scientific discourse" by implying that the existence of the FBOE is debatable, as your wording implied, because the existence of the FBOE is well-established and it is one of the most consistent findings in sexual orientation research. This is not about taking sides; this is about accurately reporting what research has found and not giving undue weight to an opinion that is not supported by the majority of research.


 * What do you mean by "Plenty of researchers do not accept it as the final say?" If you mean that researchers do not believe the FBOE to be the only reason for homosexual orientation in males, then that is correct. Studies on the FBOE do not claim so, rather the studies (and consequently the Wiki article) state that only a proportion of homosexual males owe their sexual orientation to the fraternal birth order effect. If you mean that "plenty of researchers" do not accept the existence of FBOE then that would be misleading. Only a few studies have been unable to detect the FBOE and even that does not necessarily mean that their author/researcher does not accept the existence of the FBOE (e.g., Kishida and Rahman, 2015 reported that they failed to find a FBOE in their dataset but did not rule out the existence of the FBOE. Additionally, Anthony Bogart was unable to find the FBOE in one of his studies, but he did consistently find it in his other studies and he has stated numerous times that the FBOE is one of the most consistent biodemographic correlates of sexual orientation in men ).


 * Please quote where in Kishida and Rahman (2015) does it say that Blanchard and others' criticism of Frisch and Hviid (2006) was "unfounded." Also kindly cite studies that state that Blanchard's criticisms of Frisch and Hviid (2006) were unfounded (you mentioned that other researchers said this, so citing their studies where they said it should not be difficult).


 * By "Frisch has responded" I'm assuming you are talking about Frisch (2007), correct? Frisch's (2007) reply to Blanchard's (2007) critique of Frisch and Hviid (2006) does not respond to all criticisms of Frisch and Hviid (2006). Additionally, Kishida and Rahman (2015), Frisch and Hviid (2006) and the few other studies that were unable to detect the FBOE have been critiqued in detail by Blanchard and Vanderlaan (2015). No one has argued that criticisms present in Blanchard and Vanderlaan (2015) are unfounded. The most important fact that you have overlooked is that Blanchard and Vanderlaan (2015) showed that Kishida and Rahman (2015), Frisch and Hviid (2006) and another study actually do demonstrate the FBOE. And as I stated above, Kishida and Rahman (2015) did not rule out the existence of the FBOE, rather they stated that "an FBO effect may be latent in this and other datasets but simply very difficult to detect." Regarding the reputable journal argument, all the studies that support the existence of the FBOE (and the studies critiquing Frisch and Hviid, 2006) have been published in reputable journals too. I am not in favor of presenting Frisch and Hviid (2006) as a study that supposedly disproves the existence of the fraternal birth order effect when the FBOE was found in that study upon re-analysis. Notice that I myself haven't mentioned it in the article as a study that found the FBOE. Your warning in the last line was unnecessary. –Human10.0 (talk) 15:54, 8 September 2017 (UTC)


 * Human10.0, thanks for taking the time to make your case with sound arguments about the literature. I understand Rafe87's point of view, but we have to follow the literature with WP:Due weight. As for Rafe87 questioning your conflict of your interest, that is a valid concern to have...per WP:COI. James Cantor, for example, is in the habit of declaring his COI. He also very likely has a lot of knowledge on this particular topic. Flyer22 Reborn (talk) 20:20, 11 September 2017 (UTC)


 * Thank you for sharing your thoughts on this Flyer22 Reborn. I understand that concern about a COI is valid but I stated earlier that it was "unnecessary" to warn/caution me about it since I am not a researcher involved in FBOE research and I don't have a COI. I too think that James Cantor is knowledgeable on this topic. As you have pinged him, perhaps he will add to the discussion. —Human10.0 (talk) 15:40, 13 September 2017 (UTC)


 * Hi, folks; thanks for the ping. Yes, I think Human10.0 correctly captures the relevant publications, and Flyer correctly refers to DUE.  (The nature of my COI here is that I was a student/colleague of Blanchard's, and helped him do some of the math in his research on this topic.)  Although it would certainly be accurate (technically) to say that authors are not unanimous, one would have to do some very selective cherry-picking to claim that the FBOE is not widely accepted by the literature.  (Climate change is also less than unanimous, and there are folks who claim evolution is merely a theory.)  FWIW, claims such as "final say" belie a political rather than scientific view, IMO.  In science, there is no such thing as a final say on anything.  It always remains possible for something in the future to change the conclusion.  We don't find the best available answers by just cheering for our own side and citing only those who agree...especially in place of discussing the actual evidence.— James Cantor (talk) 16:54, 18 September 2017 (UTC)


 * When I see that someone does not believe in climate change, I have to shake my head in an "Are you serious?" fashion. Flyer22 Reborn (talk) 20:48, 18 September 2017 (UTC)


 * When most people refer to "climate change," they mean global warming, as somewhat noted in the Global warming article. But either way, my aforementioned head shaking remains. People can read the Global warming article, or its sources, to see just how in tune the scientific community is on that topic. Flyer22 Reborn (talk) 20:52, 18 September 2017 (UTC) Flyer22 Reborn (talk) 20:57, 18 September 2017 (UTC)

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Wrong information
I am not a contributor in English Wikipedia, I work in Bengali Wikipedia. But still when I was going to translate a part of that article, I had been little confused. My confusing part of that article is The fraternal birth order effect has been confirmed to interact with handedness,[19][7] as the incidence of homosexuality correlated with an increase in older brothers is seen only in right-handed males.[18][20][21][19] But I know that homosexuality is found in non right handed male of major survey. Then I checked the 20 no. reference. I got the article which had been published by elsevier. The link is in here I think it would be non-right handed males. Plz; check it. Fahim fanatic (talk) 14:18, 11 April 2018 (UTC)