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.
Sexual Orientation is Genetic
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.
Brain Structure Controls Whether a Person is Homosexual
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.
Hormone Exposure Significantly Impacts 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.
Prenatal Stress Affects Homosexuality
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.
Sexuality is Inherited
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.