Top 10 Reasons Sexual Orientation Is Not a Choice

Top 10 Reasons Sexual Orientation Is Biological and Determined in the Womb (Not a Choice)

 

In recent years, the issue concerning the origin of human sexual orientation has generated a lot of attention not only in the LGBT community, but as well as in political and scientific circles. As a result, many doctors, psychologists, scientists, and other concerned groups have attempted to develop methods and conduct researches to determine what makes homosexual become what they are. With the recent findings proving how genes affect sexual orientation, as well as the on and on failure confirming that external factors influence sexual preferences, many people are now believing that sexual orientation is truly determined at birth. In fact, 47 percent of Americans now believe that sexual orientation is innate and not a choice, according to the 2013 poll from Gallup. Here are the factors showing that our sexual orientation is already settled before our birth.

 

  1. Sexual Orientation is Genetic

 

Sexuality is in your DNA
Sexuality is in your DNA

In 1993, a group of scientists at the National Institutes of Health, which was led by Dr. Dean Hamer, claimed that genes could affect the development of same-sex orientation in men. Their study, which was published in the journal Science, investigated a selected group of 40 gay brothers. Of the 40 families who were tested, Dr. Hamer and his colleagues found that 33 of the pairs shared the same genetic markers on a region of X chromosome, known as q28. However, Dr. Hamer and his team didn’t claim to have found a “gay gene,” they just believed that their discovery of this genetic linkage is strong evidence that genes truly influence sexual orientation in men.

 

But since the study has been published, many critics found Dr. Hamer’s findings questionable. A lot of people were not convinced that genes have something to do with the sexual orientation of individuals, especially that the study had only analyzed 40 pairs of gay brothers. To gather more evidence and prove the existence of genetic components of sexual orientation, Dr. Hamer expanded his research and even collaborated with the scientists from the prestigious Whitehead Institute for Biomedical Research in Cambridge and Institute for Behavioral Genetics at University of Colorado. Their study focused on the region that had been identified in Hamer’s previous study. They examined another 33 pairs of gay brothers as well as 11 pairs of heterosexual brothers. Interestingly, their findings confirmed the previous work, which made Dr. Hamer truly confident that there is a gene (genes) of the X chromosome that predisposes a man to become a gay.

 

And just recently, a study was published in Psychological Medicine, supporting the presence of genes on Xq28, which Dr. Hamer had also previously suggested, as well as on a region of chromosome 8 influencing sexual orientation in men. This study was led by Dr. J.M. Bailey and Dr. Alan Sanders, who analyzed 409 pairs of brothers to confirm genetic contributions to sexual orientation.

 

  1. Brain Structure Controls Whether a Person is Homosexual

 

Your brain on homosexuality
Your brain on homosexuality

Of course, being gay is only partly due to genes. There are certainly other biological factors involved, including the structure of the brain. Since in the early 1990s, a number of studies have been conducted to show the link between the human brain and sexual orientation. In 1990, Dr. Dick Swab and M.A. Hofman found the difference in size of the suprachiasmatic nucleus (SCN), a tiny region in the hypothalamus that contains many different neurotransmitters, between heterosexual and homosexual men. Their findings revealed that gay men have larger SCN and more cell numbers than the straight men.

 

Another brain study has also been conducted by Dr. Simon LeVay to show the difference between the hypothalamus of straight and gay men. The study involved 41 subjects who have died of AIDS, and studied four groups of neurons, known as INAH 1, INAH 2, INAH 3, and INAH 4. The subjects were divided into three groups, where the first group comprised 19 homosexual men, the second group included 16 heterosexual men, and the third group consisted of 6 heterosexual women. And according to the findings, which were published in 1991 in the journal Science, there was no significant difference revealed between the groups in their size of INAH 1, INAH 2, and INAH 4. However, the INAH 3 was found to be larger in heterosexual men group than in homosexual men and heterosexual women groups.

 

Some other studies have also found the same significant results in other areas of the brain to determine the difference between homosexual and heterosexual men, including the size of the corpus callosum and structure of amygdala. According to the findings, the corpus callosum was larger, in average, in gay men than in straight men. In terms of the amygdala, studies found that in straight women and gay men, there were more nerve connections on the left side of amygdala, compared with the right side. But in straight men and lesbians, the results were the opposite, with more neural connections on the right side of the amygdala.

 

So, our brain was influencing our sexual orientation even before we were born. This is one of the strong evidences that explains why many gay people say they always knew they were gay.

 

  1. Hormone Exposure Significantly Impacts Sexuality

 

Hormones definitely impact development including sexuality
Hormones definitely impact development including sexuality

Experts believe that androgens, also known as male sex hormones, are responsible for masculine body characteristics in human beings, as well as in animals. They also believe that if an individual is deprived of testosterone at an early stage of his life, he could become homosexual in his adult life. Well, early experiments proved that prenatal exposure to androgens can largely affect human behavior and sexual orientation. One study that demonstrated this was done by Dr. Gunter Dorner, a German endocrinologist. In his study in the late 1970s, he used male rats as test subjects. These male rats were castrated and injected with androgens when they reached sexual maturity. As a result, these male rats effectively behaved like female rats.

 

Another example is the 1984 study done by Dr. John Money and his team. In their study, they used 30 young women with a history of congenital adrenal hyperplasia (CAH), a genetic disorder that involves a deficiency in hormones cortisol or aldetosterone, and an abnormal production of androgens. These individuals were asked to give their sexual orientation and 37% rated themselves as bisexual or homosexual. They also exhibited more masculine body and behavior.

 

Hormones have diverse chemical structures that have powerful effects in our body, including our growth, development, and responses. The results of the studies mentioned above suggest that abnormal exposure to male hormones can truly affect social behavior and sexual orientation.

 

  1. Prenatal Stress Affects Homosexuality

 

Prenatal stress can impact sexuality
Prenatal stress can impact sexuality

So, now we know that hormones have effects on how we grow and change, but do you ever wonder how and why some developing infants lack or overexpose to male hormones during pregnancy? Actually, the same question was asked by Dr. Dorner after his findings on his rat experiment were published. So to provide an answer to that question, Dr. Dorner and his team did other experimental studies to identify the factors that can cause hormone exposure variation in the womb. In 1980, Dr. Dorner and his team studied the frequency of homosexuality in males who were born in Germany before and after the Second World War. And they found out that out of 865 homosexual male subjects, majority of them were born between the critical periods of the war.

 

Not that convinced with his first experiment, Dr. Dorner did another study and achieved the same result. In his second study, Dr. Dorner used 100 bisexual or homosexual men, as well as 100 heterosexual men. All of them were asked about the possible stressful events that their mothers experienced during the time that they were being carried in the womb. Majority of the homosexual and bisexual males reported on severe stressful events that have occurred in their prenatal life. The results on these studies indicate the correlation between prenatal stress and homosexuality.

 

Several experimental studies have also been conducted supporting the findings of Dr. Dorner; for instance, the 1994 study done by Dr. Ward and his colleagues. They used pregnant rats as test subjects, which they exposed to stressful situations. When these rats gave birth, the male offspring were tested and found out that 73% of them exhibited female sexual behavior.

 

Experts believe that mothers who are exposed in stressful situations are more likely to have male child with female behavior. The reason for this is because stress causes fluctuation in hormonal levels. When a pregnant mother is stressed, her body produces high level of cortisol and low level of testosterone, which can largely affect the developing brain and body of a developing child.

 

  1. Sexuality is Inherited

 

You just inherited some sweet Gayness
You just inherited some sweet Gayness

Another biological factor that plays a role in the development of sexual orientation in individuals is heredity. Some researchers believe that homosexuality runs in families; it means that if one person in the family is homosexual, then there’s a higher chance that other member of the family may be gay. There are some evidences gathered that clearly proves that. One major study that links male homosexuality to heredity was done by researchers J. Weinrich and R. Pillard in 1986. Using a sample of 51 homosexual men and 50 heterosexual men, they found out that their gay men subjects had far more than gay brothers than their straight men subjects had. From that finding, they concluded that “there is a significant familial component to male homosexuality.”

 

Other studies with similar objective have confirmed the findings of Weinrich and Pillard, including the 1998 study done by Bailey and Pillard entitled Human Sexual Orientation Has A Heritable Component, as well as the 1999 study done by the same researchers entitled A Family History Study Of Male Sexual Orientation Using Three Independent Samples. Both are published on PubMed.

 

  1. Birth Order Significantly Impacts Odds of Being Queer

 

One of these guys loves show tunes.
One of these guys loves show tunes.

The fraternal birth order effect is also one of the reasons why there are gay men. According to several studies, each older brother increases the chances of the next son of being gay, by at least 33 percent. This is because when a woman is pregnant, especially with a boy, her body can see the fetus as a foreign object and try to attack it, usually at the fetus brain that links to sexual orientation, by producing antibodies against it. The more male son a woman has, the more adept her body becomes to attack the fetus inside her, which increases her chance to give birth to a gay son. In a nutshell, the more boys, the higher the chance the next son will be gay.

 

Studies were performed by some scientists to prove this hypothesis. And one major experimental study was done by Ray Blanchard, a professor of psychology at the University of Toronto. Together with his team, Blanchard collected a certain number of heterosexual and homosexual men, and all of them were asked some significant questions about their sexuality. After the test was done, they found out that the homosexual men subjects had more older brothers than the heterosexual men subjects. So this shows that fraternal birth order is a significant predictor of sexual orientation.

 

  1. Sexual orientation Isn’t Learned

 

I learned that sexuality isn't taught that's what I learned
I learned that sexuality isn’t taught that’s what I learned

Sexual orientation is biological in nature and cannot be changed by learning some ways to be attracted to another person. Do you know a gay person who went through an education process that taught him how to be attracted with the opposite sex? I don’t think any one does that, at least for me. Well, I know that you see some gay men who are in a relationship with a woman, but that doesn’t mean that their sexuality is changed – and that they’ve learned to alter their sexuality by awareness or lessons. As experts emphasize, homosexuals and heterosexuals remain to be who they are regardless of their sexual behavior. A person who has a homosexual orientation remains “homosexual” even if that person has sex with the opposite sex. A person with heterosexual orientation remains “straight” even if that person never has sex with anyone.

 

One major case that can prove that sexual orientation isn’t learned but inborn concerned the child named Bruce Reimer. Bruce was born a normal boy, but he was raised as a girl because his penis was accidentally destroyed during a botch circumcision when he was a few months old with no possibility that it could be reconstructed. The family got so worried that their boy would live a doomed life without the male organ, so they consulted numerous medical specialists for a solution. Then there came Dr. John Money, a psychologist at Johns Hopkins University. He advised the family to raise Bruce as a girl, and so they did. They even changed his name to “Brenda.”

 

Well, it’s true that after some years, Brenda or Bruce developed some kind of female characteristics. Dr. Money even published an article that the case of Bruce was evidence that gender identity can be learned. But Dr. Money misrepresented many facts. In reality, Bruce never wanted his female identity. He hated wearing girl dresses and seeing his breast developed. He disliked his long hair and every doll that his family bought for him, and eventually demanded to rebuild his genitals. He, then discontinued to use the name Brenda, and adopted a new name, David.

 

  1. Sexual Orientation Can’t Be Treated (And Shouldn’t Be)

 

Jesus commands you not to be gay. Don't be gay.  Screw Jesus.  Hmmmm...
Jesus commands you not to be gay. Don’t be gay. Screw Jesus. Hmmmm…

Many anti-gay groups, particularly in religious community, promote the concept that an individual can change his or her sexual orientation by either religious efforts or medical treatments. Well, while there are now treatments, such as “conversion therapies,” available claiming that they can change a person’s sexual orientation, experts declare that these treatments are not effective, and in fact, are harmful. After all, there haven’t been scientific evidences gathered proving that these treatments are successful.

 

Contrary to what many people believe, being gay is not a disease; therefore, it can’t be treated or cured. It’s already part of human existence that people can’t change or abolish ever. All those treatments that claim to modify one’s sexual orientation do nothing but to teach these people to deny and hate who they truly are. It destroys their true identify and self-esteem. In fact, the American Psychological Association (APA) published a report saying that “there really is no evidence that orientation can change, (or that you can change) who you’re attracted to or who you fall in love with.”

 

And if, for instance, a male person with a homosexual orientation decides to undergo such treatment and successfully obtains “male characteristics” doesn’t mean that this person’s sexual orientation is truly changed. Remember the case of Bruce Reimer? As mentioned, sexual orientation is biologically natural, same as with our race and hair color. Our hair can be dyed to look another way, but it will always grow back in its natural hue. Likewise, we can hide our true identity by changing our behavior or dressing differently, but our real sexual orientation will always be part of us, no matter what.

 

  1. Sexual Orientation Isn’t A Choice.

 

Sexuality isn't a multiple choice test
Sexuality isn’t a multiple choice test

Human beings cannot choose to be either straight or gay. Just as what the Human Right Campaign Organization wrote on their website, “…Sexuality and gender identity are not choices any more than being left-handed or having brown eyes or being heterosexual are choices. They are a part of who you are.” Although individuals can choose how they live or whether to act or not on their feelings, experts do not consider sexual orientation to be a conscious choice that can be changed whenever you want to.

 

If you’re not yet convinced, though, try to ask straight people when did they choose to be heterosexual? Or better yet, ask yourself when did you decide to be a heterosexual or homosexual? Can you give a quick answer? No. And the same is true when you ask other people, they will completely unable to answer that question. Why? Simple. Because these people understand that their sexual orientation is natural – and not something that they choose.

 

And just think about those gay people who were forced by their parents to become straight. Most of them, even if they have tried to become what their parents wanted them to become – just to please them – they still remain homosexuals. Even if they have been put under pressure and things like that, they still remain gay. Just as what the lyrics of the controversial song, Same Love, say, “I can’t change even if I tried…even if I wanted to…”

 

As mentioned, we can choose how we want to live our lives and even express ourselves in a way that makes us feel comfortable, but our sexual orientation – our inner identity – is something that is beyond our control.

 

  1. Homosexuality is a Function of Biology: Here’s the Science

 

Homosexuality is Biological.  Here is the Science
Homosexuality is Biological. Here is the Science

There are other studies demonstrating that biology plays a major role in determining a person’s sexuality and one example is the pheromone study conducted in Sweden. This study was conducted by the researchers of the Karolinska Institute in Stockholm, Sweden, led by Dr. Ivanka Savic. Dr. Savic and her team used 36 subjects that were divided into three groups of 12 each: heterosexual men, homosexual men, and heterosexual women. Each of them was asked to sniff series of odors while their brain activities were being scanned. And the results of the research were the following: When the homosexual men and heterosexual women were exposed to the smell of testosterone, a part of their brain that plays a role in sexual response was activated. Same happened when the heterosexual men were exposed to the smell of estrogen.

Another study was the Eye Blink Inhibition study conducted by Dr. Qazi Rahman and his team in London. They collected and studied different groups of individuals to determine if there are differences between the responses of male and females, as well as of heterosexuals and homosexuals. The subjects were exposed to different levels of noise while researchers measured their eye-blink responses.  After the test, Dr. Rahman and his team found out that “the reaction of the lesbian test subjects was closer to that which would be expected among straight men. And, gay men reacted closer that of women, although to a lesser extent.”

These findings clearly show that sexual orientation is biological, fixed, not learned, and not a choice.

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  • Zach

    i feel like looking at a couple of these, his arguments collapses on its self, if you read and pay attention it just seems to me like some kinda contradict

  • Well Keked

    Identical twin studies prove homosexuality is not genetic

    Eight major studies of identical twins in Australia, the U.S., and Scandinavia during the last two decades all arrive at the same conclusion: gays were not born that way.

    “At best genetics is a minor factor,” says Dr. Neil Whitehead, PhD. Whitehead worked for the New Zealand government as a scientific researcher for 24 years, then spent four years working for the United Nations and International Atomic Energy Agency. Most recently, he serves as a consultant to Japanese universities about the effects of radiation exposure. His PhD is in biochemistry and statistics.

    Identical twins have the same genes or DNA. They are nurtured in equal prenatal conditions. If homosexuality is caused by genetics or prenatal conditions and one twin is gay, the co-twin should also be gay.

    “Because they have identical DNA, it ought to be 100%,” Dr. Whitehead notes. But the studies reveal something else. “If an identical twin has same-sex attraction the chances the co-twin has it are only about 11% for men and 14% for women.”

    Because identical twins are always genetically identical, homosexuality cannot be genetically dictated. “No-one is born gay,” he notes. “The predominant things that create homosexuality in
    one identical twin and not in the other have to be post-birth factors.”

    Dr.Whitehead believes same-sex attraction (SSA) is caused by “non-shared factors,” things happening to one twin but not the other, or a personal response to an event by one of the twins and not the other.

    For example, one twin might have exposure to pornography or sexual abuse, but not the other. One twin may interpret and respond to their family or classroom environment differently than the other. “These individual and idiosyncratic responses to random events and to common environmental factors predominate,” he says.

    The first very large, reliable study of identical twins was conductedin Australia in 1991, followed by a large U.S. study about 1997. Then Australia and the U.S. conducted more twin studies in 2000, followed by several studies in Scandinavia, according to Dr. Whitehead.

    “Twin registers are the foundation of modern twin studies. They are now very large, and exist in many countries. A gigantic European twin register with a projected 600,000 members is being organized, but one ofthe largest in use is in Australia, with more than 25,000 twins on the books.”

    A significant twin study among adolescents shows an even weaker genetic correlation. In 2002 Bearman and Brueckner studied tens of thousands of adolescent students in the U.S. The same-sex attraction concordance between identical twins was only 7.7% for males and 5.3% for females—lower than the 11% and 14% in the Australian study by Bailey et al conducted in 2000.

    In the identical twin studies, Dr. Whitehead has been struck by how fluid and changeable sexual identity can be.

    “Neutral academic surveys show there is substantial change. About half of the homosexual/bisexual population (in a non-therapeutic environment) moves towards heterosexuality over a lifetime. About 3% of the present heterosexual population once firmly believed themselves to be homosexual or bisexual.”

    “Sexual orientation is not set in concrete,” he notes.

    Even more remarkable, most of the changes occur without counseling or therapy. “These changes are not therapeutically induced, but happen ‘naturally’ in life, some very quickly,” Dr. Whitehead observes. “Most changes in sexual orientation are towards exclusive heterosexuality.”

    Numbersof people who have changed towards exclusive heterosexuality are greater than current numbers of bisexuals and homosexuals combined. In other words, ex-gays outnumber actual gays.

    The fluidity is even more pronounced among adolescents, as Bearman and Brueckner’s study demonstrated. “They found that from 16 to 17-years-old, if a person had a romantic attraction to the same sex, almost all had switched one year later.”

    “The authors were pro-gay and they commented that the only stability was among the heterosexuals, who stayed the same year after year. Adolescents are a special case—generally changing their attractions from year to year.”

    Still, many misconceptions persist in the popular culture. Namely, that homosexuality is genetic – so hard-wired into one’s identity that it can’t be changed. “The academics who work in the field are not happy with the portrayals by the media on the subject,” Dr. Whitehead notes.

    “But they prefer to stick with their academic research and not get involved in the activist side.”

    For those who are looking for Dr. Whitehead’s writings on his research visit:
    http :// www . mygenes . co . nz / download . htm

  • André

    EIGHT MAJOR IDENTICAL TWIN STUDIES PROVE HOMOSEXUALITY IS NOT GENETIC

    Eight major studies of identical twins in Australia, the U.S., and Scandinavia during the last two decades all arrive at the same conclusion: gays were not born that way.

    “At best genetics is a minor factor,” says Dr. Neil Whitehead, PhD. Whitehead worked for the New Zealand government as a scientific researcher for 24 years, then spent four years working for the United Nations and International Atomic Energy Agency. Most recently, he serves as a consultant to Japanese universities about the effects of radiation exposure. His PhD is in biochemistry and statistics.

    Identical twins have almost the same genes or DNA. They are nurtured in equal prenatal conditions. If homosexuality is caused by genetics or prenatal conditions and one twin is gay, the co-twin should also be gay.

    “Because they have almost identical DNA, it ought be close to 100%,” Dr. Whitehead notes. But the studies reveal something else. “If an identical twin has same-sex attraction the chances the co-twin has it are only about 11% for men and 14% for women.”

    Because identical twins are always genetically identical, homosexuality cannot be genetically dictated. “No-one is born gay,” he notes. “The predominant things that create homosexuality in one identical twin and not in the other have to be post-birth factors.”

    Dr.Whitehead believes same-sex attraction (SSA) is caused by “non-shared factors,” things happening to one twin but not the other, or a personal response to an event by one of the twins and not the other.

    For example, one twin might have exposure to pornography or sexual abuse, but not the other. One twin may interpret and respond to their family or classroom environment differently than the other. “These individual and idiosyncratic responses to random events and to common environmental factors predominate,” he says.

    The first very large, reliable study of identical twins was conductedin Australia in 1991, followed by a large U.S. study about 1997. Then Australia and the U.S. conducted more twin studies in 2000, followed by several studies in Scandinavia, according to Dr. Whitehead.

    “Twin registers are the foundation of modern twin studies. They are now very large, and exist in many countries. A gigantic European twin register with a projected 600,000 members is being organized, but one ofthe largest in use is in Australia, with more than 25,000 twins on the books.”

    A significant twin study among adolescents shows an even weaker genetic correlation. In 2002 Bearman and Brueckner studied tens of thousands of adolescent students in the U.S. The same-sex attraction concordance between identical twins was only 7.7% for males and 5.3% for females—lower than the 11% and 14% in the Australian study by Bailey et al conducted in 2000.

    In the identical twin studies, Dr. Whitehead has been struck by how fluid and changeable sexual identity can be.

    “Neutral academic surveys show there is substantial change. About half of the homosexual/bisexual population (in a non-therapeutic environment) moves towards heterosexuality over a lifetime. About 3% of the present heterosexual population once firmly believed themselves to be homosexual or bisexual.”

    “Sexual orientation is not set in concrete,” he notes.

    Even more remarkable, most of the changes occur without counseling or therapy. “These changes are not therapeutically induced, but happen ‘naturally’ in life, some very quickly,” Dr. Whitehead observes. “Most changes in sexual orientation are towards exclusive heterosexuality.”

    Numbersof people who have changed towards exclusive heterosexuality are greater than current numbers of bisexuals and homosexuals combined. In other words, ex-gays outnumber actual gays.

    The fluidity is even more pronounced among adolescents, as Bearman and Brueckner’s study demonstrated. “They found that from 16 to 17-years-old, if a person had a romantic attraction to the same sex, almost all had switched one year later.”

    “The authors were pro-gay and they commented that the only stability was among the heterosexuals, who stayed the same year after year. Adolescents are a special case—generally changing their attractions from year to year.”

    Still, many misconceptions persist in the popular culture. Namely, that homosexuality is genetic – so hard-wired into one’s identity that it can’t be changed. “The academics who work in the field are not happy with the portrayals by the media on the subject,” Dr. Whitehead notes.

    “But they prefer to stick with their academic research and not get involved in the activist side.”

    References
    1. Whitehead, N; Whitehead, BK (1999): My Genes Made Me Do It! Huntington House, Layfayette, Louisiana. See also: http :// www . mygenes . co . nz / download . htm
    2. Whitehead, N. “Neither Genes nor Choice: Same-Sex Attraction Is Mostly a Unique Reaction to Environmental Factors” [Journal of Human Sexuality 3: 81-114 (2011)].
    3. Whitehead, N. “The Importance of Twin Studies”, http :// narth . com /2010/09/the-importance-of-twin-studies/, accessed 5/30/13.
    4. American Psychological Association. (2008). Answers to your questions: For a better understanding of sexual orientation and homosexuality; accessed 5/28/13.
    5. The National Association for Research and Treatment of Homosexuality, “NARTH Position Statements,” http :// narth . com /2010/11/narth-position-statements/, accessed 5/30/13.
    6. Michael J. Bailey, Michael P. Dunne, and Nicholas G. Martin, “Genetic and Environmental Influences on Sexual Orientation and Its Correlates in an Australian Twin Sample,” Journal of Personality and Social Psychology 78 (March 2000): 524-536.
    7. Jeffrey Satinover, Homosexuality and the Politics of Truth, 185-187.
    8. Rosaria Champagne Butterfield, The Secret Thoughts of an Unlikely Convert, Pittsburgh, PA: Crown and Covenant, 2012.
    9. Bailey, JM; Pillard,RC (1991): A genetic study of male sexual orientation. Arch. Gen. Psychiatry48, 1089-1096.
    10. Bailey, JM; Pillard,RC; Neale,MC; Agyei,Y (1993): Heritable factors influence sexual orientation in women. Arch. Gen. Psychiatry 50, 217-223.
    11. Hershberger, SL (1997): A twin registry study of male and female sexual orientation. J. of Sex Research 34, 212-222.
    12. Bailey, JM; Dunne,MP; Martin,NG (2000): Genetic and Environmental influences on sexual orientation and its correlates in an Australian twin sample. J. Pers. Social Psychology 78, 524-536.
    13. West, DJ (1977): Homosexuality Reexamined. 4th ed. Duckworth, London.
    14. Bailey, NM; Pillard,RC (1995): Genetics of human sexual orientation. Ann. Rev. Sex Research 6, 126-150.
    15. Kendler, KS; Prescott,CA (1998): Cocaine use, abuse and dependence in a population-based sample of female twins. Brit. J. Psychiatry 173, 345-350.
    16. Rhee, SH; Waldman,ID; Hay,DA; Levy,F (1999): Sex differences in genetic and environmental influences on DSM-III-R attention-deficit/hyperactivity disorder. J. Abnorm. Psychology 108, 24-41.
    17. Green, R (1987). The “Sissy Boy Syndrome” and the Development of Homosexuality. Yale University Press, New Haven, Connecticut.
    18. Bell, AP; Weinberg,MS; Hammersmith,SK (1981): Sexual Preference: Its Development In Men and Women. Indiana University Press, Bloomington, Indiana.
    19. Homosexuality ‘may be triggered by environment after birth’ – http :// www . telegraph . co . uk /science/2016/03/15/homosexuality-may-be-triggered-by-environment-after-birth/