Twins: Is this true? (Serious question)?

Question

That in a high percentage of cases, one or both is gay.

Is this only with identical twins?

Woah!
Didn`t think I`d get this reaction.

A twin actually told me this, and he was adamant about it.
Guess I shouldn`t believe everything I hear.

Answer 1

It is true that if one twin is gay it is MUCH more likely that both will be gay -- but it is not true that twins as a group are more likely to be gay.

An example study would be: "Homosexual Orientation in Twins: A Report on 61 Pairs and Three Triplet Sets" by Whitam, Diamond and Martin (1993) which showed that in 61 pairs of twins, there were 14 pairs of male-male dizygotic (i.e. fraternal) twins. 4 of their 14 twin brothers were also homosexual (28.6 percent), while 10 were heterosexual. There were also 34 pairs of monozygotic (i.e. identical) male twins. 22 of their twin brothers were homosexual (64.7 percent), 10 were heterosexual and 2 were sort-of bisexual and inconclusive.

Other studies have backed up these findings, for example, the Bailey and Pillard study in 1991 found that 51% of the identical twin brothers of homosexual men were also homosexual, and several percentage points more were bisexual.

Now before anyone objects to this and claims that if they are identical and one is homosexual the other one would have to be if homosexuality is genetic, do at least an undergraduate level study of what genetic penetrance is. It explains the reasons for the variation very clearly.

Now, NONE of these studies indicate or show a higher rate of homosexuality among identical or fraternal twins as a whole -- only among those where one brother is indeed gay. A few studies have also been done on sisters, but I am not conversant with those studies or their results, so will defer to those who may be.

I hope that helps, feel free to contact me if you have more precise questions, I am not a geneticist or even a biologist, but I have colleagues who are, and I certainly have access to top level research materials from those fields.

Kind regards,

Reynolds Jones
[e-mail]

Answer 2

Identical twins have exactly the same genes. Fraternal twins share only as many genes as any brother or sister.

Because twins are born at the same time, the environment is as same as possible for them. So if something happens more often in identical than in fraternal twins, then it is most likely because they share the same genes.

A number of studies have looked at homosexuality in twins, all with similar results. For example, in one study, if one identical twin was gay, the other was also gay 50% of the time. If they were fraternal twins, they were both gay 22% of the time. And if one was adopted, the chances fell to 11%.

Now these numbers are from one study. Other studies have different percentages but the same trend—identical twins are more likely to both be gay as compared to fraternal twins.

Answer 3

Histrionics aside, several studies support this assertion, at least in males.

Our best research shows that the incidence of homosexuality is male identical twins is 40-50%. Incidence in male fraternal twins is 10-20%. This compares to an incidence of 4-8% in the general population.

Answer 4

I know a pair of hot identical twins and I'd give anything if at least one of them was gay, but apparently that's not the case.

I've read where sometimes several siblings in one family can be gay, but there's no pattern that I've ever heard of. My girl cousins are twins and both are happily married.

It's an intriguing theory but I know of no evidence that it's true except by coincidence.

Answer 5

Hi fella,

I think you got the wrong end of the question of conversation. If one of the twin is gay, then it is extremely likely that the other brother is gay. And if one is bisexual or straight, then it is very likely than the other is same. Though with bisexual twins the enviroment has a part to play, as I have seen two bisexual twins with one leading a straight life and other gay life, with the gay one tell me that they both have discussed this and admitted that in reality to both bisexual. The sexuality of a person is determined by hormons in during pregnancy and not twins or otherwise (see references).

Answer 6

That's bullshit. I've got twins in my family (over 15 pairs of twins actually) and I've got over 10 twins I grew up with or are now friends with. NONE are gay. Let me repeat that "NONE" are gay nor have gay tendencies. So, frankly, just because one twin set told you this does not in any way mean other twins are the same. You should know by now that the world is cookie-cutter. There are differences out there so open your eyes.

Answer 7

No, that's untrue. However, research has been carried out on identical twins who were raised in separate families. Interestingly, it seems that this suggests environment has little affect on whether a particular twin turns out to be gay - suggesting that being gay is genetic, but not the only factor.

Answer 8

I don't know the source, but I think you are referring to a study that concluded that if one identical twin was gay, the odds of the other twin being gay were much higher than it would be among fraternal twins or other sibings. I don't know where you could find this study, or if the findings were ever replicated.

Answer 9

I've met many twins and none have been gay. Being a twin would not have anything to do with whether or not you find a person of the same sex attractive. It's all personal preference. Each to their own I say.

Answer 10

This is most definately NOT TRUE!!! I know this because my mother and aunt are identical twins. I know for a fact that they have both been happily married to members of the opposite sex for many years and neither have any interest,(sexually), with members of the same sex.