if one twin is gay, what is the likelihood the other one is?

[bobbieinok]

in the case of fraternal twins?? identical twins??

[Deja Q]

1. Should it matter at all?

People are people. We don't need eugenics, we don't need fixing, we are not criminal, we are not devalued, we are not less than people.

Period.

[unblock]

4. yeah, let's stay ignorant

i think it's an interesting question aside from any political implications one way or the other.

although, as long as the haters claim that it's a matter of choice, the fact that having a gay idential twin is a significant predictor of homosexuality strongly suggests that dna is at least a major determinant. this would serve to undermine the "choice" argument, although i agree that there should be no stigma associated with that "chioce" regardless.

[Maat]

21. My husband and I are 'straights,' and my hubby agrees with you,

I believe, as he doesn't believe that we should even get to the point of worrying about the origins of sexual orientation.

He emphatically states that if two competent adults decide to pair up, it is nobody's business but their own, and they should be able to experience the benefits of the 'default contract' that is marriage/civil-unions/domestic-partnerships. For that is what 'marriage' et al is; it delineates the relationship in the absence of unique and private contractual agreements between the parties.

[unblock]

2. google is your friend

http://www.worldpolicy.org/globalrights/sexorient/twins.html

Twin studies and homosexuality

--------------------------------------------------------------------------------

Bailey and Pillard (1991): occurrence of homosexuality among brothers
52% of identical (monozygotic) twins of homosexual men were likewise homosexual
22% of fraternal (dizygotic) twins were likewise homosexual
11% of adoptive brothers of homosexual men were likewise homosexual
J.M. Bailey and R.C. Pillard, “A genetic study of male sexual orientation,” Archives of General Psychiatry, vol. 48:1089-1096, December 1991.

Bailey and Pillard (1993): occurrence of homosexuality among sisters
48% of identical (monozygotic) twins of homosexual women were likewise homosexual (lesbian)
16% of fraternal (dizygotic) twins were likewise homosexual
6% of adoptive sisters of homosexual women were likewise homosexual
Bailey, J. M. and D. S. Benishay (1993), “Familial Aggregation of Female Sexual Orientation,” American Journal of Psychiatry 150(2): 272-277.

[HockeyMom]

5. Just our family

Sister-in-law has set of fraternal twins; boy and girl. The boy is gay, but the girl isn't. However, their older sister is gay, while their younger sister is straight.

In the case of twins, fraternal twins are just the same genetically as older or younger siblings. I guess my sister-in-law's twins bear this out.

[insleeforprez]

11. 50%?!?!

about 50% of gay identical twins are gay themselves (you know what I'm trying to say...) That is very significant, that is not random.

However, you could also argue (devil's advocate) that identical twins receive similar upbringings, so some of the "factors" for being gay (a distant father, for example), would be present in both twins.

However, the big jump between the % of identical vs. fraternal twins may be more significant; fraternal twins would also theoretically get similar upbringings, so the only major difference between identical and fraternal twins is genetic.

This could really use further study....too bad there aren't a whole lot of gay twins (5% gay * 3% twin=0.15% of the population)

[Maat]

19. This is why they go to ... I want to say Scandinavian studies.

There, information on families is much more complete. I'm a retired social worker, with an M.A. in Psychology. We always focused on these studies, because they keep track of adopted kids, and their location .. and are/were able to put great studies together.

I'm trying to find a study now .. but they HAVE, I believe, come up with data strongly indicating that that sexual orientation has a strong genetic component, and things are played out during development in the uterus. The data definitely defeats the notion that there is some kind of choice after birth.

[BR_Parkway]

18. Wow, looks like 1 out of 3 twins will be gay. Something humorous

there, I'm just not sure what.

Depending on if you start with one egg or two.

[saracat]

3. Hmm. I had a good friend who was gay and his fraternal twin

was agressively hetero. He used to say it proved it wasn't genetic or upbringing, but that was his opinion.

[joeybee12]

6. For what it's worth, known two sets of identical gay twins in my life...

...never knew any identical twins who did not share the same sexual orientation.

A friend, however, just had fraternal twin girls--I'll let you know about that in 20 years!

[Warpy]

9. I did, four sets, as a matter of fact

who were taking part in bone marrow transplant experiments in the early days of untreatable HIV to see if the transplant would stop the disease (it didn't). In all four cases, one twin was gay and HIV positive and the other was straight and HIV negative.

There are quite a few gays of both sexes among my cousins, much higher rate than in the general population. My guess is that it's a combination of genetic predisposition and uterine hormonal environment during gestation.

I just know it's not a choice.

[joeybee12]

10. Interesting thing about cousins...

...my mother had two brothers--each has a gay son, and then there's me. What are the odds?

[Maat]

20. I agree with that ... combination of genetics ..

and how that plays out in development in utero.

That is what I remember the competent studies indicated when I was in my master's program.

Trying to find the data now.

[bliss_eternal]

7. Alexandra Paul

from Baywatch (think this is her name--the only actor on the show w/dark hair and no breast implants). Anyway, she's a twin and her sister is gay. I think they are identical. I knew a set of male fraternal twins personally, one was gay--one was not.

But I wouldn't dare to think these two isolated examples were indicative or anything larger that one could base anything on.:shrug:

I hope this is helpful. :hi:

[bobbieinok]

8. curious b/c of family in Europe

[SoKalKyle]

12. I had a friend....

Who was one of five kids (4 boys and a girl) and he was worried because he had to 'come out' to his folks. His worry was that all of his brothers and his sister were gay and his folks were ok with it and he felt he would 'destroy' his parents if they knew he was gay too - what had they done to get 5 gay kids. (as far as I know they were all single births).

Never found out what happened....

[davidinalameda]

14. 5 gay kids

wow

[joeybee12]

15. I'd heard of a story where the parents decided to divorce because

each realized he/she was gay, so they told the kids, who then came out. Don't know if this is an urban legend, but would make a great sitcom!

[La Lioness Priyanka]

13. my brother and i are both bi

ok so i didnt answer the question...but its weird that we both are bi

[MadAsHellNewYorker]

16. I know two identical brothers

one gay one straight

[cboy4]

17. Well, my bro-in-law is straight and

his identical twin brother is gay. Very interesting!

[DarkTirade]

22. The only gay identical twin I ever knew

had a very straight brother. So who knows.
Ironically enough, in order to tell them apart when they were infants, their mother painted one of their toenails pink.
The ironic part being that that was the twin that turned out straight. :)