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Is Homosexuality Genetic?

Written by:  • Edited by: Paul Arnold
Updated Nov 21, 2009 • Related Guides: Identical Twins | DNA

There is no clear cut answer to the origin of homosexual behaviour. Currently the consensus is leaning towards a largely genetic basis with a few environmental variables thrown in. It appears there is no single gay gene and no single environmental variable.

Is there a Gay Gene?

While homosexuality is still a touchy subject in some circles, it is more widely accepted than it was ten years ago. Researchers are still intrigued, however, with the ‘why’ behind a person’s individual attraction to someone of the same sex. The question of whether or not homosexuality is genetic has yet to be answered as most researchers have not found any true biological basis to base their own studies on. Researchers and scientists do believe, though, that homosexuality actually stems from a combination of biological and environmental factors.

Causes of Homosexuality

Sexual orientation is an incredibly complex area, but some researchers have tried to find a single genetic or environmental cause for homosexuality. This now does not seem to be the case according to the latest findings (June 2008) from the world's largest study of twins.

The work was carried out by Dr Niklas Langstrom and colleagues at the Karolinska Institute in Sweden and the studies were of all adult (20-47 years old) twins in Sweden. Many genetic studies use identical and non-identical twins to tease out genetic and environmental influences. Identical twins share the same genes and environment and non-identical twins share half their genes and all their environment. If there is a greater similarity in trait between identical twins compared to non-identical twins, genetic factors are deemed largely to be responsible. So if scientists observe that same-sex behaviour is more common amongst identical twins, then there must be genetic factors at work.

In this research the scientists asked all participants (same-gender twin pairs) about their sexual orientation and amount of same sex and opposite sex partners they had slept with

They found that genetics accounted for about 35 per cent of the differences between men in homosexual behaviour and non-shared environmental factors about 64 percent.

In homosexual women, 18 per cent of the variation in same-sex behaviour was accounted for by genetics, non-shared environment 64 percent and shared environment about 16 per cent.

Nature or nurture

Although specific genes were not identified researchers believe they operate somewhere during development; an analysis of DNA should be able to provide some answers. Clearly from this latest research both nature and nurture play a role in homosexual behaviour.

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Comments

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brown paddy May 25, 2011 6:13 AM
confusion reigns!!
homosexuality is not a western or developed world phenomena. it is ignorant to think that is true. sure, it is more visible in the more liberated societies but it is just as prevalent in the conservative societies, albeit hidden from view.

there is a genetic predisposition to every aspect of human expression, be it physical, physiological or behavioral. but all these are moderated by the environment (physical, emotional, social, cultural, religious, etc.) which is constantly evolving. hence the presented behaviour is a result of nature-nurture interactions. most behaviours are learned at a very early age (0-4 yrs). this is also true for the development of our sexuality which is a learned behaviour. hence our sexual orientation is also determined at a very early age.

there is no right or wrong type of sexual orientation. the question is what is 'acceptable' or the 'norm' in the environment that a person lives in. there is no universal code for that. the thing to remember is that the 'liberated western' societies also comprise large populations that still believes that homosexuality is a 'sin' as would any other 'conservative easterner'.
bro Apr 22, 2011 7:47 PM
RE: Is Homosexuality Genetic?
It's amazing hwo even educated ppl are swayed and brainwashed into believeing that it is inherent or innnate. IT's absolutely nurture, this behavior is prominent mainly in western culture, and rare in many other coutnries and evironments. How come it is not prominent in other regions in the world, it just proves that exposure to that mentality as young heterosexual may confuse him into thinking it is ok, and starts thinking as such, and with time you have deviance. It is a result of maladaptation, exposure, gender identity disorder, and allowance. It's indeed amazing on how ppl can chew on garbage. intercourse is defined as one gender with the opposite gender, the rest is emulation. the only group that should be confused are hermaphrodite
Dave Apr 2, 2011 10:40 PM
A long process
Based upon personal experience, I would agree that it's partially genetic and partially environment/nuture. Since a teen I tended to notice other guys but did not have the freedom to express it. The expectation of the community I grew up in was men marry women and have a family. I married but my eyes wandered and noticed men (never other women) and my fantasies were male oriented. Finally at the age of 43 I admitted I was attracted to other men.
Coming from a conservative Christian background, this was incredibly difficult to admit but I also knew how much prayer and counseling had gone into trying to change my attractions. Finally some counselors and my pastors shared that I could continue to try and repress, suppress and deny the attractions, but that would be like trying to swim upstream - it takes a lot of effort and very little progress is made.
My conclusion: I've tried to change and the attractions have gone nowhere. I've gone to Exodus like ministries and heard even from them that they don't expect homosexual men to become heterosexual; they hope gay men will cease risky behavior (i.e, be celibate). Isn't that a double-edged sword to hear from the conservative side that being gay is a sin but don't expect God to change you. It's easier for me to say like David in the Psalms, "I am fearfully and wonderfully made."
Sue Mar 8, 2011 11:20 PM
prenatal biological wiring
Regarding homosexuality, there is a lot of ignorance. Apparently, studies are showing that it's prenatal biological wiring in the womb which comes from a abnormal hormonal setting. Also, the brains are not the same in size actually smaller than heterosexuals. Also, you are dealing with the opposite spirit in your body. There is gay behavior in animals as well which was incorrectly stated above. Long time ago heterosexuality was becoming extinct, that is why God said what he did. His people had no clue of what was right and wrong. God's people left their natural ways, for they stopped worshiping God. "True homosexuals" have a man and a woman in their sexuality genders. There are three sexualities...hetero, homo and asexual. It is a matter of time before these are recognized, and all will have the same rights, as marital civil unions. All should be blessed in monogamous loving Christ centered relationships. No sexuality is better than the other, for we are all children of God. Oh, and Jesus did not utter a word of condemnation against gays. Jesus is God, our personal Savior.
JD Feb 18, 2011 4:39 PM
Genetic predisposition
No genes have been isolated for it. It's that simple at this time. The species is maintained by sexual attraction and homosexuality doesn't fit. Career criminals are a social abberation and we don't try to find a gene to explain that yet many criminals start when young. I'll buy choice, confusion, environment etc but not genetic. I know of two sets of identical twins where one is homosexual. This is not consistent with genetic predisposition.
brown paddy Jan 22, 2011 7:44 PM
i'll go with lifestyle choice
All research is based on limited available samplings, hence inconclusive. in this case we r talking about people revealing their sexual orientation to researchers. when we r subjected to analysis we tend to conform to expectations. so how true are the 'facts' gathered? also trying to tie a behaviour to a gene is more fiction than fact. from experience, i believe homosexuality can result from an aborted desire to experiment with and explore our sexuality during adolescence. this creates a malformed ideation about sex. the environment then becomes instrumental in deciding sexual orientation by offering the more readily accessible partners for sex. in most societies it happens to be individuals of the same gender. some people then continue to form same sex relationships, others reject it after going thru the experience, still others are comfortable with both. in liberal societies such alternate lifestyles are more visible as there is no pressure to conform. in more conservative ones people 'choose' straight relationships. so there, nurture mostly with nature only providing the genetic soup which can be accused of anything.
daughter Dec 10, 2010 5:14 AM
i feel my family should be studied
When i was in middle school i found out that my father was gay, which was okay to me as long as my parents stopped fighting.
The day after this revelation, I found out that ALL of my dad's brothers were gay as well. He has 3 brothers in all, and there is a 12-14 year gap in their ages.
Clearly this prevalence between siblings is not common. But they did not grow up in the same house at all.
In the end, my personal experience heavily contributes to my opinion on the matter
Michael Sep 22, 2010 9:07 PM
Propagation of the Species
Human survival suggests that human's (much like any other species) must propagate to survive. So the baseline to all research should be from the propagation of the species angle. With that being said; since gay relationships are far more frequent nowadays, are researchers suggesting that mankind is genetically changing such that eventually we can become extinct? I doubt it. The fact remains that propagation of the species is "genetic", anything outside of that is "environment". Humans (or any other species) simply don't evolve into a state that ensures their extinction.
Michael Aug 7, 2010 12:54 AM
hmm
Animals do engage in homosexualality..but human sexuality and relationships are far to complex (and animal not so complex) to draw any meaningful conclusions from. How many straight people have the chromosome variation? Attraction is a learned trait. The enviroment one finds themself in plays a huge, if not exclusive role, in defining what kind of person you are attracted to. We arent born prefering blondes with blue eyes, over tall and dark..we figure it out as we go along, and we tend to be attracted to those similar and familiar to us...
Rob Jul 21, 2010 3:47 PM
genetic vs.environment
I have three sons. My middle son is gay. The other two are very much the opposite. My mother has two sisters, each with a gay grandson. I tend to think this there is a strong genetic component to this. I hope there are more studies done on this so these men can find more peace in the society they have to live in.
Larryt Blong Jul 1, 2010 1:14 AM
Environment-Free Will
The mind can talk you into anything. God (if you don't believe in one forget everything I'm saying), made the sexual act to be between a man and a woman (that's how babies get here). It's probably mostly in your upbringing. Notice that animals don't engage in that behavior. Why is is it more prevalent now than in the 1800's? It's a choice and a lifestyle. It takes a man to capture a woman. Maybe they should try being more of a man. What does the Bible say? Most of these gay folks are pretty God-less I think. We all have free will so don't give me the I'm made to do it!
Bokul Apr 17, 2010 7:50 AM
comments
From the beginning of my teenage I found myself, my physical attraction towards boys.My bilogical thinking always ran to same aged boys.My fantasy also go through to the other boys.At night I dreamed them.Now Im 22 years old, studing UNIVERSITY OF DHAKA, still think about other boys. I took many councelling to change me as a straight but always faild. Trying to be straight always make me mentally disorderd but as a gay Im very happy about me.SO I think behaving gayism is natural and genetic.But there is differences between gayism and homosexuality, because behavior is difference.
Paul Arnold Aug 22, 2009 1:28 PM
Nature and Nurture
It is both, though the consensus is toward largely genetic. According to the study featured here, which was published in 2008, the larger influence was environmental. I expect that the nature and nurture ratios will change over the years as other researchers look into the subject i.e. will it be 50-50/, 70-30, 60-40 etc? It highlights how complex are studies looking for a genetic basis of behaviour.
Billy Aug 22, 2009 12:54 PM
which is it
the current consensus leaning toward a largely genetic basis? but based on the twin studies you cited doesn't it say that the environment plays a larger factor? Did I understand that correctly?
 
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