# Does Anyone Believe Sexual Preference is 100% Genetic? **URL:** \ **Category:** Great Debates\ **Created:** [July 3, 2012, 2:26pm UTC](https://boards.straightdope.com/t/does-anyone-believe-sexual-preference-is-100-genetic/627100 "2012-07-03T14:26:18Z")\ **Posts on this page:** 20\ **Page:** 5
**Author:** ![NojNoj](https://avatars.discourse-cdn.com/v4/letter/n/2bfe46/32.png) [@NojNoj](https://boards.straightdope.com/u/NojNoj)\ **Post date:** [July 3, 2012, 7:25pm UTC](https://boards.straightdope.com/t/does-anyone-believe-sexual-preference-is-100-genetic/627100/81 "2012-07-03T19:25:37Z")
> [@chorpler](#): > > What you’re arguing against sounds more like the whole “blank slate” thing; that’s the theory that led to David Reimer’s problems. Yes, I was too quick to respond. I was taught brain structure was not controlled by hormonal influence but directly related to genetics. The article you link to says that even though the people with the deficiency have female sex characteristics, they still have male gender identity (consistent with them being genetically male), which is also consistent with brain formation assuming a gender by way of some other mechanism… ---
**Author:** ![Marley23](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@Marley23](https://boards.straightdope.com/u/Marley23)\ **Post date:** [July 3, 2012, 7:27pm UTC](https://boards.straightdope.com/t/does-anyone-believe-sexual-preference-is-100-genetic/627100/82 "2012-07-03T19:27:23Z")
> [@NojNoj](#): > > Maybe so…I just think politically he would have had a greater chance of “winning over” more people who were somewhere in the middle by sticking to the “this is another form of love…” argument. And I think you’re wrong. If he were signing that bill today, he might say something like that. As you noted, he made those comments in 2004, and the issue was seen very differently at the time. A lot has changed. ---
**Author:** ![NojNoj](https://avatars.discourse-cdn.com/v4/letter/n/2bfe46/32.png) [@NojNoj](https://boards.straightdope.com/u/NojNoj)\ **Post date:** [July 3, 2012, 7:34pm UTC](https://boards.straightdope.com/t/does-anyone-believe-sexual-preference-is-100-genetic/627100/83 "2012-07-03T19:34:04Z")
> [@Marley23](#): > > And I think you’re wrong. Yup, arguing for sake of arguing… (So the heathens who lived back in the dark ages of 2004 would no way have understood the argument that “homosexuality is another form of love.” Good thing you reject assertions without evidence (all’s I said was I think he would have had a better chance…)) ---
**Author:** ![Marley23](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@Marley23](https://boards.straightdope.com/u/Marley23)\ **Post date:** [July 3, 2012, 7:40pm UTC](https://boards.straightdope.com/t/does-anyone-believe-sexual-preference-is-100-genetic/627100/84 "2012-07-03T19:40:16Z")
> [@NojNoj](#): > > So the heathens who lived back in the dark ages of 2004 would no way have understood the argument that “homosexuality is another form of love.” I didn’t say nobody would have understood it. I said I think that argument would have been less effective in 2004, when this issue was even more polarizing. Anti-gay marriage initiatives were on a lot of state ballots that year, and Vermont was one of the first states to allow civil unions. Several more states have followed suit, and it’s been almost a decade. Today a lot of people think letting gay couples get married is common sense, and the number of people who felt that was in 2004 was much smaller. > [@](#): > > all’s I said was I think he would have had a better chance… Better chance of what? Vermont voters evidently agreed with him already. He made those comments while signing into law a bill that legalized civil unions in the state. ---
**Author:** ![Minnie\_Luna](https://avatars.discourse-cdn.com/v4/letter/m/4bbf92/32.png) [@Minnie\_Luna](https://boards.straightdope.com/u/Minnie_Luna)\ **Post date:** [July 3, 2012, 7:47pm UTC](https://boards.straightdope.com/t/does-anyone-believe-sexual-preference-is-100-genetic/627100/85 "2012-07-03T19:47:22Z")
From my last cited paper: > [@](#): > > HY antigen almost certainly has some role or roles in the sexual differentiation of vertebrates because it is usually present in the heterogametic and absent in the homogametic sex (in mammals, present in males and absent in females) and because it has been highly conserved throughout > vertebrate evolution. The possible involvement of HY antigen > in the development of sex-typical traits suggests that fetal exposure to H-Y antibodies could affect subsequent sexual behavior in men. > [@](#): > > The second question was whether H-Y antibodies could be present in sufficient quantities to affect the sexual differentiation of the fetal brain without also > affecting the development of the genitalia. In mice, testes can develop in the complete absence of H-Y antigen. It is therefore plausible that the genitalia could develop normally in human males whose H-Y antigen is only partly bound > by H-Y antibodies[ \*\*Lemur 866 Anyway, plenty of people with homosexual orientations have kids. Homosexuality isn’t as strongly negative to reproductive fitness as people tend to think. \*\* Biologically yes, but behaviorally no. Biologically speaking, exposure to H-Y antigen in male fetal mice **is** linked to reduced reproductive fitness and it appeared to be more behavioral in nature than a result of structural anomalies. The immunized males had normal sex organs and testes, but failed to respond to females in estrous or when they did respond they were unable to properly mount or failed to thrust and thus failed to ejaculate. They were perfectly biologically capable of sexual reproduction, they just didn’t do it. I do see the evolutionary advantage (to the older male siblings and mothers) having no reduction in the number of younger males, but making them less likely to reproduce. ---
**Author:** ![NojNoj](https://avatars.discourse-cdn.com/v4/letter/n/2bfe46/32.png) [@NojNoj](https://boards.straightdope.com/u/NojNoj)\ **Post date:** [July 3, 2012, 8:00pm UTC](https://boards.straightdope.com/t/does-anyone-believe-sexual-preference-is-100-genetic/627100/86 "2012-07-03T20:00:59Z")
@Minnie Luna So is it fair to say that how a fetal brain develops gender-related structure is, at present, unknown? (But again, I thought I had read somewhere it was directly controlled by genetics.) That something is “plausible” is certainly far from “lots of evidence.” And I said above, that XY people who are afflicted with 5-alpha reductase deficiency still self-identify as males, in spite of having female sex organs, to me strongly argues that the brain acquires gendered characteristics from a completely different mechanism. ---
**Author:** ![Shagnasty](https://avatars.discourse-cdn.com/v4/letter/s/9dc877/32.png) [@Shagnasty](https://boards.straightdope.com/u/Shagnasty)\ **Post date:** [July 3, 2012, 8:19pm UTC](https://boards.straightdope.com/t/does-anyone-believe-sexual-preference-is-100-genetic/627100/87 "2012-07-03T20:19:01Z")
> [@NojNoj](#): > > That something is “plausible” is certainly far from “lots of evidence.” And I said above, that XY people who are afflicted with 5-alpha reductase deficiency still self-identify as males, in spite of having female sex organs, to me strongly argues that the brain acquires gendered characteristics from a completely different mechanism. You are taking specific cases and applying it to a whole bunch of biological phenomenon without justification. I am not sure why you keep saying that people with androgen insensitivity disorders self-identify as males when they that is completely false. Many ‘females’ with the disorder don’t even know they are genetically male unless a medical professional catches it when other problems like lack of menstration are reported. Look at this group of AIS (genetically male) women. Do they look like they self-identify as males to you? > **[File:Women with androgen insensitivity syndrome.jpg](https://en.wikipedia.org/wiki/File:Orchids01.JPG)** > > Click on a date/time to view the file as it appeared at that time. > You cannot overwrite this file. The following 2 pages use this file: > The following other wikis use this file: I am trying to keep this basic and at the picture level because you haven’t even begun to realize how much you don’t know yet. The body of knowledge isn’t complete yet but it is huge already. This is fully developed scientific field across many disciplines including the hard sciences with thousands of researchers involved. Grabbing random examples and misrepresenting what you think they mean doesn’t show anything. ---
**Author:** ![NojNoj](https://avatars.discourse-cdn.com/v4/letter/n/2bfe46/32.png) [@NojNoj](https://boards.straightdope.com/u/NojNoj)\ **Post date:** [July 3, 2012, 8:28pm UTC](https://boards.straightdope.com/t/does-anyone-believe-sexual-preference-is-100-genetic/627100/88 "2012-07-03T20:28:01Z")
> [@Shagnasty](#): > > This is fully developed scientific field across many disciplines including the hard sciences with thousands of researchers involved. Grabbing random examples and misrepresenting what you think they mean doesn’t show anything. I’m not grabbing random examples, I’m casting a critical eye on the evidence that was offered. The poster mentioned 5 Alpha Reductase deficiency as showing the importance of hormonal involvement in pre-natal brain development. They cited a Wikipedia article. The Wikipedia article says most XY individuals identify as males (citations below). This doesn’t support the hypothesis that the deficiency effects brain structure in the same way it effects physical sex characteristics–in fact it supports the opposite. Where is the evidence that brains acquire a gender-specific structure through hormonal involvement? (I’m sincerely open to learning about it, but have only seen unsupported assertions on this point. And the Reimer case does negate the idea that you can just flip a hormonal switch early in life and change someone’s gender. But let’s see evidence regarding prenatal dynamics.) ^ Praveen, EP; Praveen EP, Desai AK, Khurana ML, Philip J, Eunice M, Khadgawat R, Kulshreshtha B, Kucheria K, Gupta DK, Seith A, Ammini AC. (February 2008). “Gender identity of children and young adults with 5alpha-reductase deficiency.”. J Pediatr Endocrinol Metab. 21 (2): 173–179. PMID 18422030. ^ Imperato-Mcginley, Julianne; Julianne Imperato-McGinley, M.D., Ralph E. Peterson, M.D., Teofilo Gautier, M.D., and Erasmo Sturla, M.D. (May 31, 1979). “Androgens and the Evolution of Male-Gender Identity among Male Pseudohermaphrodites with 5α-Reductase Deficiency”. New England Journal of Medicine 300 (22): 1233–1237. DOI:10.1056/NEJM197905313002201. PMID 431680. ---
**Author:** ![Shagnasty](https://avatars.discourse-cdn.com/v4/letter/s/9dc877/32.png) [@Shagnasty](https://boards.straightdope.com/u/Shagnasty)\ **Post date:** [July 3, 2012, 8:46pm UTC](https://boards.straightdope.com/t/does-anyone-believe-sexual-preference-is-100-genetic/627100/89 "2012-07-03T20:46:20Z")
> [@NojNoj](#): > > (I’m sincerely open to learning about it, but have only seen unsupported assertions on this point. And the Reimer case does negate the idea that you can just flip a hormonal switch early in life and change someone’s gender. But let’s see evidence regarding prenatal dynamics.) Ok, if you are sincere about wanting to learn some basics, the link below is to a decent college level introduction to brain sexual differentiation in humans. It is a lot more productive to make sure we have the 101 level stuff covered before we start debating specific clinical cases. It is the Cliff notes version of college level books on the subject. [Sexual differentiation of the human brain in relation to gender identity and sexual orientation.](http://www.shb-info.org/sexbrain.html) ---
**Author:** ![NojNoj](https://avatars.discourse-cdn.com/v4/letter/n/2bfe46/32.png) [@NojNoj](https://boards.straightdope.com/u/NojNoj)\ **Post date:** [July 3, 2012, 8:53pm UTC](https://boards.straightdope.com/t/does-anyone-believe-sexual-preference-is-100-genetic/627100/90 "2012-07-03T20:53:36Z")
Sorry, that’s not a course, it’s an advocacy group making their case. (E.g., “There is no proof that social environment after birth has an effect on gender identity or sexual orientation.” offered without any support, and something a lot of people would disagree with.) Please address the evidence cited in the Wikipedia article. You authoratatively declared it’s false that “people with androgen insensitivity disorders self-identify as males.” Explain the discrepancy between your assertion and Wikipedia and its references. ---
**Author:** ![chorpler](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chorpler/32/2888_2.png) [@chorpler](https://boards.straightdope.com/u/chorpler)\ **Post date:** [July 3, 2012, 8:53pm UTC](https://boards.straightdope.com/t/does-anyone-believe-sexual-preference-is-100-genetic/627100/91 "2012-07-03T20:53:58Z")
Of course, 5α reductase deficiency is only one of the types of androgen insensitivity syndromes that can result in XY-genotyped individuals developing with a female phenotype. The Wikipedia article on [Androgen insensitivity syndrome](http://en.wikipedia.org/wiki/Androgen_insensitivity_syndrome) is a good place to start for looking at others. The article on [Complete Androgen Insensitivity Syndrome](http://en.wikipedia.org/wiki/Complete_androgen_insensitivity_syndrome) says: > [@](#): > > Individuals with CAIS are raised as females. **They are born phenotypically female and almost always have a heterosexual female gender identity;[40][62]** the incidence of homosexuality in women with CAIS is thought to be less than unaffected women. However, at least two case studies have reported male gender identity in individuals with CAIS. (bolding mine) The two citations for the bolded portion are: 1. Wisniewski AB, Migeon CJ, Meyer-Bahlburg HFL, Gearhart JP, Berkovitz GD, Brown TR, Money J. Complete androgen insensitivity syndrome: long-term medical, surgical, and psychosexual outcome. J Clin Endocrinol Metab. 2000;85;2664-2669 [Pubmed link](http://www.ncbi.nlm.nih.gov/pubmed/10946863) 1. Kulshreshtha B, Philibert P, Eunice M, Khandelwal SK, Mehta M, Audran F, Paris F, Sultan C, Ammini AC (December 2009). “Apparent male gender identity in a patient with complete androgen insensitivity syndrome”. Arch Sex Behav 38 (6): 873–5. DOI:10.1007/s10508-009-9526-2. PMID 19636694. [Pubmed link](http://www.ncbi.nlm.nih.gov/pubmed/19636694) It appears the first is available for free online; the second one is apparently available only to institutions with a subscription to the journal via SpringerLink. I have such a subscription, so I’ll see what it says. ---
**Author:** ![chorpler](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chorpler/32/2888_2.png) [@chorpler](https://boards.straightdope.com/u/chorpler)\ **Post date:** [July 3, 2012, 8:57pm UTC](https://boards.straightdope.com/t/does-anyone-believe-sexual-preference-is-100-genetic/627100/92 "2012-07-03T20:57:09Z")
So the first study, of 14 individuals with CAIS, [reports](http://jcem.endojournals.org/content/85/8/2664.long): > [@](#): > > _Self-perceived femininity and masculinity_. Women with CAIS overwhelmingly reported a high degree of femininity along with a low degree of masculinity throughout development. Mean femininity rating (not feminine = 1 to highly feminine = 5) for subjects during childhood was 4.4 (range, 2–5), during adolescence was 4.2 (range, 3–5) and during adulthood was 4.6 (range, 4–5). Mean masculinity rating (not masculine = 1 to highly masculine = 5) for subjects during childhood was 1.4 (range, 1–4), during adolescence was 1.4 (range, 1–3), and during adulthood was 1.1 (range, 1–2). > > _Sexual orientation_. A large majority of CAIS women reported female heterosexual orientation in terms of sexual attraction, fantasies, and experience during both adolescence (100%) and adulthood (93%). The one participant who reported homosexual attraction, fantasies, and experiences indicated that a lesbian orientation applied only to her adulthood. Clearly, in this case the development of female homosexuality was not associated with androgen exposure. ---
**Author:** ![NojNoj](https://avatars.discourse-cdn.com/v4/letter/n/2bfe46/32.png) [@NojNoj](https://boards.straightdope.com/u/NojNoj)\ **Post date:** [July 3, 2012, 8:58pm UTC](https://boards.straightdope.com/t/does-anyone-believe-sexual-preference-is-100-genetic/627100/93 "2012-07-03T20:58:15Z")
And the article you cite doesn’t even support your case: “There may also be direct genetic effects that affect the sexual differentiation of the brain without involving the sex hormone receptors. Some fetal rat brain cells undergo sexual differentiation, even in tissue culture, without the involvement of sex hormones” [this is what I was arguing–direct genetic control] “There are at present many additional candidate genes for a role in sexual differentiation of the brain without the involvement of hormones, since it has been found that fifty genes are expressed at different levels in the brains of male and female mouse fetuses, even before the hormones come into play (15). Also, genes that escape inactivation on the X chromosome (such as PCDH11X) could show sexually dimorphic expression and thus contribute to sexually dimorphic functions (16). Thus, the sexual differentiation of the brain is not caused by hormones alone, even though they are very important for gender identity and sexual orientation.” It’s clear this is an area where a lot more work needs to be done… ---
**Author:** ![Shagnasty](https://avatars.discourse-cdn.com/v4/letter/s/9dc877/32.png) [@Shagnasty](https://boards.straightdope.com/u/Shagnasty)\ **Post date:** [July 3, 2012, 8:58pm UTC](https://boards.straightdope.com/t/does-anyone-believe-sexual-preference-is-100-genetic/627100/94 "2012-07-03T20:58:45Z")
> [@NojNoj](#): > > Sorry, that’s not a course, it’s an advocacy group making their case. (E.g., “There is no proof that social environment after birth has an effect on gender identity or sexual orientation.” offered without any support, and something a lot of people would disagree with.) > > Please address the evidence cited in the Wikipedia article. You authoratatively declared it’s false that “people with androgen insensitivity disorders self-identify as males.” Explain the discrepancy between your assertion and Wikipedia and its references. 90% of the linked article is a primer on basic biology and it is not written by any type of advocacy group. I am sorry you think so but I have a feeling you just don’t want to learn something because that would be too hard yet you have no problem random pieces of it with no understanding of the basics. **chorpler** is correct. 5α reductase deficiency is only one type of the androgen insensitivity syndromes. I thought that would be self-explanatory to anyone so interested in the subject so I didn’t qualify it. The point stands. ---
**Author:** ![NojNoj](https://avatars.discourse-cdn.com/v4/letter/n/2bfe46/32.png) [@NojNoj](https://boards.straightdope.com/u/NojNoj)\ **Post date:** [July 3, 2012, 9:02pm UTC](https://boards.straightdope.com/t/does-anyone-believe-sexual-preference-is-100-genetic/627100/95 "2012-07-03T21:02:59Z")
@chorpler If you guys are harping on scientific validity, you can’t cite one study with n=14 as proof positive. (I refer back to NYT’s article on crisis in epidemiological studies.) If even the advocacy group acknowledges direct genetic involvement with sexual differentiation, it’s impossible not to conclude this field is in its infancy. ---
**Author:** ![Minnie\_Luna](https://avatars.discourse-cdn.com/v4/letter/m/4bbf92/32.png) [@Minnie\_Luna](https://boards.straightdope.com/u/Minnie_Luna)\ **Post date:** [July 3, 2012, 9:03pm UTC](https://boards.straightdope.com/t/does-anyone-believe-sexual-preference-is-100-genetic/627100/96 "2012-07-03T21:03:56Z")
> [@NojNoj](#): > > @Minnie Luna So is it fair to say that how a fetal brain develops gender-related structure is, at present, unknown? (But again, I thought I had read somewhere it was directly controlled by genetics.) > > That something is “plausible” is certainly far from “lots of evidence.” And I said above, that XY people who are afflicted with 5-alpha reductase deficiency still self-identify as males, in spite of having female sex organs, to me strongly argues that the brain acquires gendered characteristics from a completely different mechanism. Like **Shagnasty** said, there is a lot of information out there and many people working on it. Genetics is not solely responsible for brain development in any area, including gender. If it was twin studies would be able to prove it in short order. There would be no cases of identical twins where one is transgender and one is cisgender. ---
**Author:** ![Shagnasty](https://avatars.discourse-cdn.com/v4/letter/s/9dc877/32.png) [@Shagnasty](https://boards.straightdope.com/u/Shagnasty)\ **Post date:** [July 3, 2012, 9:06pm UTC](https://boards.straightdope.com/t/does-anyone-believe-sexual-preference-is-100-genetic/627100/97 "2012-07-03T21:06:00Z")
> [@NojNoj](#): > > If even the advocacy group acknowledges direct genetic involvement with sexual differentiation, it’s impossible not to conclude this field is in its infancy. Please, it is in its infancy. It is neuroscience. That doesn’t mean that some processes aren’t already well mapped out. That is the way science works. Almost all studies end with ‘more research is needed’ because science never ends. There could be some direct genetic involvement but we don’t know much about that part yet or even if it is true at all. The role of sex hormones has been well studied since the before the 1970’s - today. ---
**Author:** ![NojNoj](https://avatars.discourse-cdn.com/v4/letter/n/2bfe46/32.png) [@NojNoj](https://boards.straightdope.com/u/NojNoj)\ **Post date:** [July 3, 2012, 9:07pm UTC](https://boards.straightdope.com/t/does-anyone-believe-sexual-preference-is-100-genetic/627100/98 "2012-07-03T21:07:54Z")
> [@Shagnasty](#): > > I am sorry you think so but I have a feeling you just don’t want to learn something because that would be too hard yet you have no problem random pieces of it with no understanding of the basics. . Before you spin completely out of control, please address that fact that the article you link to clearly sees a role for “direct genetic effects” on sexual differentiation, which is what I was arguing, and which you summarily dismissed. ---
**Author:** ![NojNoj](https://avatars.discourse-cdn.com/v4/letter/n/2bfe46/32.png) [@NojNoj](https://boards.straightdope.com/u/NojNoj)\ **Post date:** [July 3, 2012, 9:18pm UTC](https://boards.straightdope.com/t/does-anyone-believe-sexual-preference-is-100-genetic/627100/99 "2012-07-03T21:18:57Z")
> [@Shagnasty](#): > > The role of sex hormones has been well studied since the before the 1970’s - today. Yes, and poorly understood as the Reimer case demonstrates. You entered this thread by unambiguously declaring “Sexual differentiation is caused directly by the sex hormones like testosterone, estrogen and DHT. Genetics only play an indirect role in sexual differentiation..:” You link to an article that clearly says something different. Why don’t you take some time to educate yourself about opposing points of view and the threshold for scientific certainty before you keep going on this path… You seem to be adopting the tactics of John Money–you make passive-aggressive ad hominem attacks, but don’t support your assertions in any way other than by saying you studied at the Ivy League and this is the way it is. (so did I, and so did Money). ---
**Author:** ![Shagnasty](https://avatars.discourse-cdn.com/v4/letter/s/9dc877/32.png) [@Shagnasty](https://boards.straightdope.com/u/Shagnasty)\ **Post date:** [July 3, 2012, 9:20pm UTC](https://boards.straightdope.com/t/does-anyone-believe-sexual-preference-is-100-genetic/627100/100 "2012-07-03T21:20:01Z")
> [@NojNoj](#): > > Before you spin completely out of control, please address that fact that the article you link to clearly sees a role for “direct genetic effects” on sexual differentiation, which is what I was arguing, and which you summarily dismissed. Some researchers are open to the possibility that there could be some direct genetic involvement on brain sexual differentiation. Little is known about it or if it plays a significant or any role at all in this. We do know about the role of sex hormones and those account for effects that are large enough that they leave only minor room for other factors in brain sexual differentiation even if they are there. You have to be careful about showing of a particular arguing style here because we don’t fall for it unlike most of the general public does. The tactic is to keep asking the scientists more and more specific questions until you finally get an answer of ‘We don’t fully understand that yet’. That is when someone jumps in and says "Ah Ha!, You don’t know everything so maybe MY ideas are the ones that are right after all’. That tactic is a favorite amount AGW deniers and you seem to be partial to it too. [Previous page](https://boards.straightdope.com/t/does-anyone-believe-sexual-preference-is-100-genetic/627100.md?page=4) [Next page](https://boards.straightdope.com/t/does-anyone-believe-sexual-preference-is-100-genetic/627100.md?page=6)