Researchers have provided evidence that gay men report having had less loving and more rejecting fathers, and closer relationships with their mothers, than non-gay men.

Keep It Real wrote:It's interesting.

Keep It Real wrote:So an Australian twin study showed there is approximately a 20% concordance for monozygotic twins and homosexuality. Clearly the environment plays a large role in the development of sexual orientation. What factors are at play?

ScholasticSpastic wrote:

Keep It Real wrote:So an Australian twin study showed there is approximately a 20% concordance for monozygotic twins and homosexuality. Clearly the environment plays a large role in the development of sexual orientation. What factors are at play?

It's not clear, though. The womb is an environment, and twins share it. Environmental influences should, therefor, be expected to increase twin concordance and thereby confound any conclusions we can draw about the genetic influences for homosexuality based upon concordance data. It's a riddle, wrapped in an enigma, pressing on a bladder.

Keep It Real wrote:So an Australian twin study showed there is approximately a 20% concordance for monozygotic twins and homosexuality. Clearly the environment plays a large role in the development of sexual orientation. What factors are at play?

In 2000 Bailey, Dunne and Martin studied a larger sample of 4,901 Australian twins but reported less than half the level of concordance.[5] They found 20% concordance in the male identical or MZ twins and 24% concordance for the female identical or MZ twins. Self reported zygosity, sexual attraction, fantasy and behaviours were assessed by questionnaire and zygosity was serologically checked when in doubt.

igorfrankensteen wrote:Here's an article specifically refuting the primary claim of this thread:

http://www.scientificamerican.com/artic ... identical/

You really shouldn't attempt to deduce anything so dramatic as that differences between "identical" twins PROVES that environment is 100% responsible for differences, before you first ask the more logical question.

How genetically identical are "identical twins," exactly?

As we see in that article, the answer is, not all that identical.

Now that we can directly map DNA, we can now see that 100% of all twin-based studies done to date, are functionally meaningless, unless the DNA of all subjects was preserved, and is now inspected, to remove all NON-identical "identical twins" from the results.

Back to the propaganda drawing board.

igorfrankensteen wrote:"Headline grabbing propaganda" in this case, otherwise known as "inconvenient facts the thread starter wants to ignore."

Bearman and Brückner (2002) criticized early studies concentrating on small, select samples[7] and non-representative selection of their subjects.[8] They studied 289 pairs of identical twins (monozygotic or from one fertilized egg) and 495 pairs of fraternal twins (dizygotic or from two fertilized eggs) and found concordance rates for same-sex attraction of only 7.7% for male identical twins and 5.3% for females, a pattern which they say "does not suggest genetic influence independent of social context."[7]

igorfrankensteen wrote:"Headline grabbing propaganda" in this case, otherwise known as "inconvenient facts the thread starter wants to ignore."

laklak wrote:Overexposure to Liza Minnelli and Cher albums at a formative age.

Keep It Real wrote:

igorfrankensteen wrote:"Headline grabbing propaganda" in this case, otherwise known as "inconvenient facts the thread starter wants to ignore."

Tiny differences. How they could account for the 20% concordance figure is....fanciful, to put it lightly. I seek the truth whereas you, apparently, seek maintenance of the statue quo: that homosexuality is derived from genetics. I don't care about the social ramifications, I just want the truth. We have to see, we have to know.

Bearman and Brückner (2002) criticized early studies concentrating on small, select samples[7] and non-representative selection of their subjects.[8] They studied 289 pairs of identical twins (monozygotic or from one fertilized egg) and 495 pairs of fraternal twins (dizygotic or from two fertilized eggs) and found concordance rates for same-sex attraction of only 7.7% for male identical twins and 5.3% for females, a pattern which they say "does not suggest genetic influence independent of social context."[7]

https://en.wikipedia.org/wiki/Biology_and_sexual_orientation