I specifically remember discussing this in my psychology class. At the time of the writing, if one twin was homosexual, you had a 60% chance of the other also being homosexual. This was in identical twins that were not raised by the same parents–which is the golden standard for determining nature vs. nurture. The assumption was that those raised by the same parents would be more likely to have the same sexuality, but, from what I read above, perhaps this is not the case.
There are many biological conditions that do not have a perfect convergence for identical twins. Handedness is an example of this.
People tend to think of “environment” as soley how someone was raised or what they endured during their formative years. But they forget that environment includes what happens in the womb too. Just like a person standing closer to the door feels drafts that a person who’s on the other side of the room does not feel, the same goes for the womb. Twin fetuses experience difference in hormonal exposure. Food isn’t equally distributed. They aren’t positioned the same. They undergo different stresses during the birthing process.
And epigenetics is also important. Identical twins start to diverge genetically the moment they split from one another.
Me three -----Identical twins that were neighbors, and their differences where pronounced even as children, Ron was artisitic and musical and had a feminine demeanor while Don was a hard-core jock
My cite would be the original Kinsey reports, and the more recent follow-up reports from the Kinsey Institute.
Kinsey reported on sexual behavior, not about people being homosexual or heterosexual. He used 7 categories to deal with the variation Musicat mentioned. And he had a whole section on effective research on sex, and how to deal with the inaccuracy or even dishonesty that Markxxx mentioned. Many more recent studies completely ignored these points.
But discussing the accuracy of the Kinsey reports needs to go off to the Great Debates section – there have been several threads on this over the years.
Oh, I just remembered another set of identical twins I vaguely know, men, one gay and one straight. They aren’t close friends of mine, so I didn’t think of them at first. But they are both very stereotypical of their sexual orientations–the gay guy has an effeminate voice and loves baking, the straight dude plays drums and walks like a cowboy. They live in the same town as the first set. I really don’t think this is particularly uncommon. There are so many factors that might affect orientation both inside and outside the womb; I don’t think variability in twins should come as a surprise.
Ok, so they’re sororal twins.