"Twin Studies and Homosexuality"

[J Sonnentag]

From the description:

Last week the claim was made that 8 twin studies supported the idea that homosexuality was not primarily genetic or determined in utero. An attempt is made to track down the evidence behind that claim and to look briefly at some other twin studies.

 

 

 

1. Bailey, M. et al. 2000. In Genetic and Environmental Influences on Sexual Orientation and Its Correlates in an Australian Twin Samples. J Pers Soc Psychol 78:524-536. Available at http://postcog.ucd.ie/files/Bailey%20et%20al.%20twins,2000.pdf
2. Bearman, P. & H. Bruckner. 2002. Opposite Sex Twins and Adolescent Same-Sex Attraction. Am J Sociology 107(5):1179-1205. Available at http://academiccommons.columbia.edu/catalog/ac:129241
3. http://religiopoliticaltalk.com/rpts-cumulative-case-why-same-sex-relationships-should-not-be-normalized/
4. Whitehead, N. E. 2014. My genes made me do it! Homosexuality and the Scientific Evidence. 3rd ed. Huntington House Publishers, Lafayette, LA. Available at http://mygenes.co.nz/download.htm - Chapter 10 (Twin studies — the strongest evidence) available at http://mygenes.co.nz/PDFs/Ch10.pdf
5. Jones, S. L. & M. A. Yarhouse. 2000. Homosexuality: The Use of Scientific Research in the Church's Moral Debate. Downer’s Grove, IL: InterVarsity Press. Not examined in this study, but synopsis used. Available at http://www.cccu.org/~/media/filefolder/2005-2007/Jones-Homosexuality_pdf.pdf
6. Bailey, J. M. & R. C. Pillard. 1991. A genetic study of male sexual orientation. Arch Gen Psychiatry, 48:1081-1096. Available at https://www.researchgate.net/profile/J_Bailey2/publication/21311211_A_genetic_study_of_male_sexual_orientation/links/02e7e53c1a72a8a596000000.pdf
7. Bailey, J. M., R. C. Pillard, M. C. Neale, & Y. Agyei. 1993. Heritable factors influence sexual orientation in women. Archives of General Psychiatry 50:217-223. Available at http://faculty.bennington.edu/~sherman/sex/female-twin-lesbian.pdf
8. Kirk, K. M., J. M. Bailey, M. P. Dunne, & N. G. Martin. 2000. Measurement models for sexual orientation in a community twin sample. Behavior Genetics 30:345-56. Available at https://genepi.qimr.edu.au/contents/p/staff/CV279.pdf
9. Buhrich, N., J. M. Bailey, & N. G. Martin. 1991. Sexual orientation, sexual identity, and sex-dimorphic behaviors in male twins. Behavior Genetics 21:75-96. Abstract available at http://link.springer.com/article/10.1007/BF01067668#page-1
10. Hershberger, S. L. 1997. A twin registry study of male and female sexual orientation. Journal of Sex Research 34:212-22. Abstract (and first page) available at http://www.tandfonline.com/doi/abs/10.1080/00224499709551886#preview
11. Santtila, P., N. K. Sandnabba, N. Harlaar, M. Varjonen, K. Alanko, & B. von der Pahlen. 2008. Potential for homosexual response is prevalent and genetic. Biological Psychology 77(1):102-5. Abstract available at http://www.sciencedirect.com/science/article/pii/S0301051107001433
12. Langstrom, N., Q. Rahman, E. Carlstrom, & P. Lichtenstein. 2010. Genetic and Environmental Effects on Same-sex Sexual Behavior: A Population Study of Twins in Sweden. Arch Sexual Behavior 39(1):75-80. Available at http://www.behavioralneuroscience.org/neurogenetics_files/Långström%20et%20al.%20-%202010%20-%20Archives%20of%20sexual%20behavior.pdf
13. Alanko, K., P. Santtila, N. Harlaar, K. Witting, K. Varjonen, P. Jern, A. Johansson, B. von der Pahlen, & N. K. Sandnabba. 2010. Common Genetic Effects of Gender Atypical Behavior in Childhood and Sexual Orientation in Adulthood: A Study of Finnish Twins. Arch Sexual Behavior 39(1):81-92. Available at https://www.researchgate.net/profile/Patrick_Jern/publication/23951519_Common_genetic_effects_of_gender_atypical_behavior_in_childhood_and_sexual_orientation_in_adulthood_a_study_of_Finnish_twins/links/54fd9f060cf270426d12c64b.pdf
14. Bailey, J. M. & A. P. Bell. 1993. Familiality of female and male homosexuality. Behavior Genetics. 23: 313-322. Available at http://link.springer.com/article/10.1007/BF01067431
15. Kirk, K. M. & J. M. Bailey. 2000. Etiology of male sexual orientation in an Australian twin sample. Psychology, Evolution & Gender. 2(3): 301-311. Available at https://genepi.qimr.edu.au/contents/publications/staff/CV284.pdf
16. Alanko, K., B. Salo, A. Mokros, & P. Santilla. 2013. Evidence for Heritability of Adult Men's Sexual Interest in Youth under Age 16 from a Population-Based Extended Twin Design. J Sex Med 10(4):[No pages listed]. Available at https://www.researchgate.net/publication/235369954_Evidence_for_Heritability_of_Adult_Men%27s_Sexual_Interest_in_Youth_under_Age_16_from_a_Population-Based_Extended_Twin_Design
17. http://www.councilforresponsiblegenetics.org/ViewPage.aspx?pageId=74#IIC
18. Kendler, K., L. M. Thornton, S. E. Gilman, et al. 2000. Sexual orientation in a U.S. national sample oftwin and non-twin sibling pairs. American Journal of Psychiatry. 157(11):1843-1846. Available at http://ajp.psychiatryonline.org/doi/full/10.1176/appi.ajp.157.11.1843

 

 

[Stan]

that is true...  there is not identifiable  gay gene that has been discovered,,,,,  yet.

 

The amount of gays in twins, have been very high and very measurable.

[Bravus]

On the other hand, if someone has a gay twin they have a higher chance of being gay than is the case for the overall population, even if raised in a different environment.

The twin study evidence is frustrating for both 'sides', because what it shows is that being gay is neither entirely determined genetically nor entirely independent of genetics. It appears to be some combination of nature and nurture.

Given that there is some genetic component, however, the claim that it is entirely a matter of free choice does not seem to fit the available evidence.

The experience with 'conversion therapies', and the large rates of 'de-conversion' and suicide tends to point in a similar direction.

[GayatfootofCross]

hmmmmm

 

[Bravus]

Many assertions, contrary to the evidence. 

Opinions are not facts. 

[Bravus]

Quote

My opinion is a gay gene makes no sense. We should see entire generations if Gay families. The next impossibility for a gay gene is because Gays can't procreate a gay gene can't exist. We also don't see generations if Gay people. Well, again, we can't see generations of gay people...imagine that.

If it is a gene then it isn't from God but a mutation through sin.

OK, so you're having a bet each way, but either way you win? Nice work if you can get it. There's no gene, but even if there is a gene it means what you think it means.

Your statements about a gay gene and heredity just display deep ignorance of heredity and genetics. About 4-10% of the population are gay, and gay people are born to straight parents and vice versa. There's no 'true breeding gay line', but there needn't be.

I've actually stipulated further up the thread that there is not a single 'gay gene' that is present in gay people and absent in straight. But there is also no single 'eye color gene': eye color is determined by a complex interaction of up to 15 genes. Sexuality may be similarly complex, and that would be unsurprising.

What the twin studies do show is that there is some genetic component. Simply dismissing that based on prejudice is an ignorant response.

[Bravus]

Please link these studies. It's what I have been asking for all along: more than unsupported assertions.

Studies please.

[Bravus]

Where do all our behaviours come from? There is an enormous range. Some are from Eden and some from the Fall. Heterosexual behaviours can be loving or abusive. It is that dimension - the motivations and the harms - that makes something good or evil.

Homosexual behaviours can also be loving or abusive. You assume without evidence that all homosexual behaviours are harmful, immoral or ungodly.

There is no harmless rape, incest or paedophilia, but there is harmless - indeed, highly beneficial - homosexual love. Your slippery slope fallacy is just that, a fallacy.

[Bravus]

It is, and Google Scholar is an even more amazing one, because it yields quality peer reviewed evidence, not opinions.

See, the thing is, I have made a pretty extensive and scholarly study of this topic, and have come to the conclusions presented in this thread: there is no single gene, but there is a genetic component.

The reason I'm asking for your studies is that, if there is good quality evidence that contradicts my position, I need to know that in order to change my position.

If you can point me to quality research demonstrating that there is no genetic component in sexuality, I'll be very grateful.

[Bravus]

Then we are saying the same thing. (Assuming that you would accept that some part of the 'tendency' is genetic.)

The genetic arguments, as I said near the beginning of the thread, are not definitive either for or against, so it may actually be better to abandon them and discuss the issues on other grounds.

[Bravus]

If you wish to make a Biblical argument then you will need to do so, rather than assume the Bible agrees with your opinion.

Animals and children cannot give free and informed consent, so those slippery slope arguments are fallacious as well as offensive.

The Bible seems actually very cool with polygamy, except for deacons/pastors, so if the Bible is the source of your code you shouldn't have issues with it.

Believing that someone is made with blue eyes is not an accusation against God. Neither is being made homosexual *unless* you assume already that being homosexual is wrong: something you have not argued or established.

[Bravus]

What doctrine was Jesus teaching here? What is the point of the story?

What doctrine was Jesus teaching in the parable of the rich man and Lazarus? What was the point of the story?

If you don't subscribe to an eternally burning hell with conscious people in it, because it is an incidental detail of that latter story, not the point of the teaching, then it also does not make sense to establish doctrine about marriage based on an incidental detail in this story.

What Jesus is teaching here - the point of the story - is the importance of lifelong committed relationships. It could certainly be argued that people of the same sex can commit to the same kinds of relationships. 

The teaching is 'if you marry, stick together'. Perhaps divorce in the church would be a topic of discussion that would be worthwhile... but there seems to be a lot less appetite for it.

[Bravus]

Of course. Nothing that effects a small proportion of the population is the norm, by definition. But by the same token, red hair, which has a similar incidence, is a difference, not a defect. 

Sexual identity is complex and fluid, typically more so for women than men. I have actually published (well, am one author on a multiauthored paper) on exactly this question. The full version of the paper is available here: http://espace.library.uq.edu.au/view/UQ:316910

The 'Kinsey scale' places everyone on a continuum from same-sex attracted to opposite-sex attracted. Many people are out near the ends of the scale, in either direction, but some are closer to the middle and more flexible. They will tend to fall in love with a person, rather than a sex, and may have different relationships across their lives. 

I am not arguing that sexuality is genetically determined, I am saying that it is genetically influenced. That seems to accord with the facts. There are many other influences, including culture and biography. Many people who are gay by inclination have been forced into unhappy 'straight' lives by social pressure. It seems much less prevalent, but it's possible someone could be forced into a gay life by social pressure I suppose.

Interestingly, the rate of homosexuality among the adult children of same-sex couples is about the same as in the rest of the population. If it was all nurture it would seem probable that rate would be higher.

[Bravus]

Again, you are defining homosexuality as objectionable in making arguments that it is objectionable.

Circular reasoning.

[Bravus]

The fact that someone is not a Christian in the same way that you are a Christian does not make them not a Christian.

The only thing that matters is whether we are a Christian the same way Jesus was a Christian.

 

[Bravus]

Deleted post.

Edited March 16, 2016 by David Geelan
I don't think it's ethical for me to act as a moderator in a discussion I'm in the middle of.

[Green Cochoa]

The Bible's clarity on the homosexuality question leaves little room for discussion.  It pronounces it an "abomination" (see Leviticus 18:22; 20:13), on a par with sacrificing one's children as a burnt offering (see Deuteronomy 12:31).  For a follower of Christ to teach others that one of the things God holds as detestable is simply a matter of personal choice, or even that he or she was "born with it" so it is "OK" is itself astonishing.  Jesus told us what He thought should happen to such a one.  We are all born sinners.  We all have the duty, obligation, and privilege of finding freedom from our sins, both inherited and cultivated, through Jesus Christ our Lord.

[Bravus]

Picking up sticks on Sabbath was also an abomination worthy of stoning, and wearing clothes of mixed fibres is mentioned in the same couple of chapters of Leviticus. Let him who is without sin cast the first stone.

[Bravus]

Jesus told us nothing of the sort, by the way. Don't put words in His mouth that were never there.

[Green Cochoa]

4 minutes ago, David Geelan said:

Picking up sticks on Sabbath was also an abomination worthy of stoning, and wearing clothes of mixed fibres is mentioned in the same couple of chapters of Leviticus. Let him who is without sin cast the first stone.

I don't advocate stoning, but neither would I advocate committing adultery--which was the situation where Jesus made that famous statement about casting the first stone.  The commandments are clear.  

[Bravus]

Actually, it turns out not so much. The words used in both the OT and NT texts do not refer to loving adult same-sex relationships we are talking about now, but to various forms of temple prostitution and other rites related to other gods. There is a very strong argument, for those reading the texts in the original languages and without prejudice, that in fact there is not a Biblical prohibition against same-sex relationships in general. In both places, what is prohibited is more like 'sexual idolatry'.

[Green Cochoa]

3 minutes ago, David Geelan said:

Actually, it turns out not so much. The words used in both the OT and NT texts do not refer to loving adult same-sex relationships we are talking about now, but to various forms of temple prostitution and other rites related to other gods. There is a very strong argument, for those reading the texts in the original languages and without prejudice, that in fact there is not a Biblical prohibition against same-sex relationships in general. In both places, what is prohibited is more like 'sexual idolatry'.

Please do not misunderstand me here, but I am going to illustrate what it appears to me that you are implying by saying this here--no offense intended, and these questions are not serious ones, simply rhetorical to illustrate the point.

Do you rape your wife?  Do you have intercourse with her in an "unloving" way?  If so, would this not be sinful?

Now, back to the discussion: you have said that "the OT and NT texts do not refer to loving adult same-sex relationships."  Well, let's look at one of those texts.

Quote

If a man also lie with mankind, as he lieth with a woman, both of them have committed an abomination: they shall surely be put to death; their blood [shall be] upon them. Leviticus 20:13

It would appear to me that the Bible does indeed address a "loving" relationship, for it compares it to the kind that would normally occur between a husband and a wife, a man and a woman.  

[Bravus]

J Sonnentag? Paul Giem?

[Bravus]

Yes, read carefully: I said the text on mixed fibres is in Leviticus.

And we're at the threats of violent death. It's where these discussions always end up when the arguments fail.

[Bravus]

I did not say that you had threatened: this is a 'my God can beat you up' argument. 

It assumes that your position is the Biblical one and mine is not. This is the persistent problem, as I noted earlier: circular reasoning. Assuming what you set out to prove.