Summary on twin tudies and SSA

In the last post I did, which was short, involved brain studies. Instead of criticizing the famous twin study, Bailey and Pillard 1991. Their analysis is highly flawed, and due to the fact I don't feel qualified to criticize this study I will merely post a link where professionals refute its findings (http://www.trueorigin.org/gaygene01.asp).

Now, many twin studies have argued biology causes homosexuality. Ironically, this is a mere illusion and the majority of twin studies find environmental factors cause homosexuality. And onto the list.

• "[This]  paper, however, finds  using twin studies, that chance (nonshared environmental factors) is indeed predominant,  and shows that biological factors—like genetic factors—are likely to contribute less than  20% of the variance in the development of SSA"

 Whitehead, Neil E. "Neither Genes nor Choice: Same-Sex Attraction Is Mostly a Unique Reaction to Environmental Factors." Journal of Human Sexuality (2011)

• "These very complex comparisons of identical twins and non-identical twins definitively rule out genetic determinism. Identical twins with identical genes are about 11-14% concordant for SSA. If homosexuality were “genetic,” identical co-twins of homosexual men and women would also be homosexual 100% of the time. In classic twin studies the genetic fraction is less than 23% for men and 37% for women, and may be as low as 10%. Twin studies continue to find steadily lower genetic input into homosexuality as methodology improves and samples become larger. Everyone has at least a 10% genetic influence in their behavior— because without genes there can be no human behavior of any kind. Twin studies show that individualistic reactions to chance events (in which one identical twin reacts differently from the other) are by far the strongest contributors to homosexuality. In other words personal individual reactions to random events are a strong factor."

 Whitehead, Neil, and Briar Whitehead. My Genes Made Me Do It!: [a Scientific Look at Sexual Orientation]. Lafayette, LA: Huntington House, 1999.
*Note I used the 2010 updated version of this book, which can be read for FREE online

• "Twin studies are favorites of mine because of the potential light they throw on the origins of same-sex attractions (SSA). The latest one (Santtila et al., 2008) is three times larger than any previous study - in fact, larger than all the rest put together. ... Are genetic contribution results of say 27% important? No. In the twin studies world the influence would be classified as weak to modest. And any influence is indirect - it is likely to be something like an innate tendency to be very sensitive to the opinions of others. However, even this weak or modest genetic contribution is probably greatly overstated. ... The results, by my calculations, do in fact, reinforce one conclusion drawn from previous studies. That is, if one identical twin--male or female--has SSA, the chances are only about 10% that the co-twin also has it. In other words, identical twins usually differ for SSA."

Whitehead, Neil E. "Latest Twin Study Confirms Genetic Contribution To SSA Is Minor." Latest Twin Study Confirms Genetic Contribution To SSA Is Minor. National Association for Research & Therapy of Homosexuality, 2008. Web. 07 Oct. 2012. <http://narth.com/docs/isminor.html>.

• "The cordance rate for homosexuality in non-twin biologic brothers was only 9.2 percent—significantly lower than that required by a simple genetic hypothesis, which, on the basis of shared genetic material, would predict similar concordance rates for dizygotic twins and non- twin rates were similar for nontwin biologic brothers (9.2 percent) andgenetically unrelated adoptive brothers (11.0 percent) is at odds witha simple genetic hypothesis, which would predict a higher concor-dance rate for biologic siblings."

 Byne, William, and Bruce Parsons. "Human Sexual Orientation: The Biologic Theories Reappraised." Archives of General Psychiatry 50 (1993)

• "For men, no significant genetic effects were found for number of opposite- and
  same-sex sexual encounters, nor for sexual orientation."

 Hershberger, Scott. "A Twin Registry Study of Male and Female Sexual Orientation." The Journal of Sex Research. 1997.

Out of the hundreds of studies that support my position, I only cited a few. However, if readers wish to continue I highly recommend this book available in PDF format. It reviews thousands of studies and concludes homosexuality is not genetic (http://www.mygenes.co.nz/).